Determination of the resonance response in an engine cylinder with a bowl-in-piston geometry by the finite element method for inferring the trapped mass

[EN] Cylinder resonance phenomenon in reciprocating engines consists of high-frequency pressure oscillations excited by the combustion. The frequency of these oscillations is proportional to the speed of sound on pent-roof combustion chambers and henceforth the resonance frequency can be used to estimate the trapped mass, but in bowl-in-piston chambers a geometrical factor must be added in order to deal with the bowl disturbance. This paper applies the finite element method (FEM) to provide a resonance calibration for new design combustion chambers, which are commonly dominated by the bowl geometry near the top dead centre. The resonance calibration does not need any sensor information when it is solved by a FEM procedure, and consequently, is free from measurement errors. The calibration is proven to be independent of the chamber conditions and the results obtained are compared with experimental data by using spectral techniques and measuring precisely the trapped mass.[EN]This research has been partially supported by the European Union in framework of the POWERFUL project, seventh framework program FP7/2007-2013, theme 7, sustainable surface transport (grant agreement number SCP8-GA-2009-234032).Broatch Jacobi, JA.; Guardiola, C.; Bares-Moreno, P.; Denia Guzmán, FD. (2016). Determination of the resonance response in an engine cylinder with a bowl-in-piston geometry by the finite element method for inferring the trapped mass. International Journal of Engine Research. 17(5):534-542. https://doi.org/10.1177/1468087415589701S534542175Powell, J. D. (1993). Engine Control Using Cylinder Pressure: Past, Present, and Future. Journal of Dynamic Systems, Measurement, and Control, 115(2B), 343-350. doi:10.1115/1.2899074Desantes, J. M., Galindo, J., Guardiola, C., & Dolz, V. (2010). Air mass flow estimation in turbocharged diesel engines from in-cylinder pressure measurement. Experimental Thermal and Fluid Science, 34(1), 37-47. doi:10.1016/j.expthermflusci.2009.08.009Finol, C. A., & Robinson, K. (2006). Thermal modelling of modern engines: A review of empirical correlations to estimate the in-cylinder heat transfer coefficient. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 220(12), 1765-1781. doi:10.1243/09544070jauto202Torregrosa, A. J., Broatch, A., Martín, J., & Monelletta, L. (2007). Combustion noise level assessment in direct injection Diesel engines by means of in-cylinder pressure components. Measurement Science and Technology, 18(7), 2131-2142. doi:10.1088/0957-0233/18/7/045Luján, J. M., Bermúdez, V., Guardiola, C., & Abbad, A. (2010). A methodology for combustion detection in diesel engines through in-cylinder pressure derivative signal. Mechanical Systems and Signal Processing, 24(7), 2261-2275. doi:10.1016/j.ymssp.2009.12.012Payri, F., Broatch, A., Tormos, B., & Marant, V. (2005). New methodology for in-cylinder pressure analysis in direct injection diesel engines—application to combustion noise. Measurement Science and Technology, 16(2), 540-547. doi:10.1088/0957-0233/16/2/029Zhen, X., Wang, Y., Xu, S., Zhu, Y., Tao, C., Xu, T., & Song, M. (2012). The engine knock analysis – An overview. Applied Energy, 92, 628-636. doi:10.1016/j.apenergy.2011.11.079Draper C. S. The physical effects of detonation in a closed cylindrical chamber. Technical report, National Advisory Committee for Aeronautics, 1938.Payri, F., Olmeda, P., Guardiola, C., & Martín, J. (2011). Adaptive determination of cut-off frequencies for filtering the in-cylinder pressure in diesel engines combustion analysis. Applied Thermal Engineering, 31(14-15), 2869-2876. doi:10.1016/j.applthermaleng.2011.05.012Hickling, R., Feldmaier, D. A., Chen, F. H. K., & Morel, J. S. (1983). Cavity resonances in engine combustion chambers and some applications. The Journal of the Acoustical Society of America, 73(4), 1170-1178. doi:10.1121/1.389261Bodisco, T., Reeves, R., Situ, R., & Brown, R. (2012). Bayesian models for the determination of resonant frequencies in a DI diesel engine. Mechanical Systems and Signal Processing, 26, 305-314. doi:10.1016/j.ymssp.2011.06.014Guardiola, C., Pla, B., Blanco-Rodriguez, D., & Bares, P. (2014). Cycle by Cycle Trapped Mass Estimation for Diagnosis and Control. SAE International Journal of Engines, 7(3), 1523-1531. doi:10.4271/2014-01-1702Torregrosa, A. J., Broatch, A., Margot, X., Marant, V., & Beauge, Y. (2004). Combustion chamber resonances in direct injection automotive diesel engines: A numerical approach. International Journal of Engine Research, 5(1), 83-91. doi:10.1243/146808704772914264Broatch, A., Margot, X., Gil, A., & Christian Donayre, (José). (2007). Computational study of the sensitivity to ignition characteristics of the resonance in DI diesel engine combustion chambers. Engineering Computations, 24(1), 77-96. doi:10.1108/02644400710718583Payri, F., Molina, S., Martín, J., & Armas, O. (2006). Influence of measurement errors and estimated parameters on combustion diagnosis. Applied Thermal Engineering, 26(2-3), 226-236. doi:10.1016/j.applthermaleng.2005.05.006Mechel, F. P. (Ed.). (2008). Formulas of Acoustics. doi:10.1007/978-3-540-76833-3Samimy, B., & Rizzoni, G. (1996). Mechanical signature analysis using time-frequency signal processing: application to internal combustion engine knock detection. Proceedings of the IEEE, 84(9), 1330-1343. doi:10.1109/5.535251Lapuerta, M., Armas, O., & Hernández, J. J. (1999). Diagnosis of DI Diesel combustion from in-cylinder pressure signal by estimation of mean thermodynamic properties of the gas. Applied Thermal Engineering, 19(5), 513-529. doi:10.1016/s1359-4311(98)00075-1FUENMAYOR, F. 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An overview of aliasing errors in discrete-time formulations of time-frequency representations. IEEE Transactions on Signal Processing, 47(5), 1463-1474. doi:10.1109/78.75724

Prune cAMP phosphodiesterase binds nm23-H1 and promotes cancer metastasis

We identify a new enzymatic activity underlying metastasis in breast cancer and describe its susceptibility to therapeutic inhibition. We show that human prune (h-prune), a phosphoesterase DHH family appertaining protein, has a hitherto unrecognized cyclic nucleotide phosphodiesterase activity effectively suppressed by dipyridamole, a phosphodiesterase inhibitor. h-prune physically interacts with nm23-H1, a metastasis suppressor gene. The h-prune PDE activity, suppressed by dipyridamole and enhanced by the interaction with nm23-H1, stimulates cellular motility and metastasis processes. Out of 59 metastatic breast cancer cases analyzed, 22 (37%) were found to overexpress h-prune, evidence that this novel enzymatic activity is involved in promoting cancer metastasis

Outcome of neuropsychiatric symptoms related to an antiretroviral drug following its substitution by nevirapine: the RELAX study

Objectives: The primary objective was to evaluate the improvement in neuropsychiatric symptoms attributed to an antiretroviral drug after that drug was substituted with nevirapine. The secondary objective was to evaluate the impact on patient adherence and quality of life. Methods: A prospective, observational study was carried out that included patients with HIV-1 plasma suppression for whom an antiretroviral drug was substituted with nevirapine because of central nervous system (CNS) side effects, a Pittsburgh Sleep Quality Index (PSQI) score > 5 or a Hospital Anxiety and Depression Scale (HADS) score ≥ 10, and who had not initiated psychoactive drug treatment during the prior 6 weeks. Evaluations were carried out at baseline and 1 and 3 months after the switch using the PSQI, HADS, Epworth Sleepiness Scale, Medical Outcomes Study-Short Form 30 items (MOS-SF-30) and Simplified Medication Adherence Questionnaire (SMAQ). Results: A total of 129 patients were included in the study. The drug substituted was mainly efavirenz (89.9%), and reasons for the switch included sleep disturbances (75.2%), anxiety (65.1%), depression (38.7%), attention disturbances (31%), and other reasons (31%), with a mean of 2.4 neuropsychiatric disturbances per patient. A statistically significant improvement was observed in all the tests evaluating neuropsychiatric symptoms and adherence at 1 and 3 months. The CD4 lymphocyte count remained stable (P = 0.096). Three (2.3%) patients had a detectable plasma HIV-1 RNA at the end of the study. Nine patients (6.9%) withdrew because of nevirapine-related toxicity (rash in seven patients and hypertransaminasaemia in two patients, none of which were > grade 2). Conclusions: The switch to nevirapine from a drug causing neuropsychiatric disturbances (primarily efavirenz) in subjects with virological suppression was effective in resolving those disturbances, with an improvement in all the parameters studied. This led to better adherence to treatment and quality of life, with no detrimental effect on their immunological and virological controlBoehringer Ingelheim Spai

Linearly scaling direct method for accurately inverting sparse banded matrices

In many problems in Computational Physics and Chemistry, one finds a special kind of sparse matrices, termed "banded matrices". These matrices, which are defined as having non-zero entries only within a given distance from the main diagonal, need often to be inverted in order to solve the associated linear system of equations. In this work, we introduce a new O(n) algorithm for solving such a system, being n X n the size of the matrix. We produce the analytical recursive expressions that allow to directly obtain the solution, as well as the pseudocode for its computer implementation. Moreover, we review the different options for possibly parallelizing the method, we describe the extension to deal with matrices that are banded plus a small number of non-zero entries outside the band, and we use the same ideas to produce a method for obtaining the full inverse matrix. Finally, we show that the New Algorithm is competitive, both in accuracy and in numerical efficiency, when compared to a standard method based in Gaussian elimination. We do this using sets of large random banded matrices, as well as the ones that appear when one tries to solve the 1D Poisson equation by finite differences.Comment: 24 pages, 5 figures, submitted to J. Comp. Phy

Genetic and pharmacological regulation of the endocannabinoid CB1 receptor in Duchenne muscular dystrophy

The endocannabinoid system refers to a widespread signaling system and its alteration is implicated in a growing number of human diseases. However, the potential role of endocannabinoids in skeletal muscle disorders remains unknown. Here we report the role of the endocannabinoid CB1 receptors in Duchenne's muscular dystrophy. In murine and human models, CB1 transcripts show the highest degree of expression at disease onset, and then decline overtime. Similar changes are observed for PAX7, a key regulator of muscle stem cells. Bioinformatics and biochemical analysis reveal that PAX7 binds and upregulates the CB1 gene in dystrophic more than in healthy muscles. Rimonabant, an antagonist of CB1, promotes human satellite cell differentiation in vitro, increases the number of regenerated myofibers, and prevents locomotor impairment in dystrophic mice. In conclusion, our study uncovers a PAX7-CB1 cross talk potentially exacerbating DMD and highlights the role of CB1 receptors as target for potential therapies

Spiked oscillators: exact solution

A procedure to obtain the eigenenergies and eigenfunctions of a quantum spiked oscillator is presented. The originality of the method lies in an adequate use of asymptotic expansions of Wronskians of algebraic solutions of the Schroedinger equation. The procedure is applied to three familiar examples of spiked oscillators

Positive selection in Europeans and East-Asians at the ABCA12 gene

Natural selection acts on genetic variants by increasing the frequency of alleles responsible for a cellular function that is favorable in a certain environment. In a previous genome-wide scan for positive selection in contemporary humans, we identified a signal of positive selection in European and Asians at the genetic variant rs10180970. The variant is located in the second intron of the ABCA12 gene, which is implicated in the lipid barrier formation and down-regulated by UVB radiation. We studied the signal of selection in the genomic region surrounding rs10180970 in a larger dataset that includes DNA sequences from ancient samples. We also investigated the functional consequences of gene expression of the alleles of rs10180970 and another genetic variant in its proximity in healthy volunteers exposed to similar UV radiation. We confirmed the selection signal and refine its location that extends over 35 kb and includes the first intron, the first two exons and the transcription starting site of ABCA12. We found no obvious effect of rs10180970 alleles on ABCA12 gene expression. We reconstructed the trajectory of the T allele over the last 80,000 years to discover that it was specific to H. sapiens and present in non-Africans 45,000 years ago

Validación de la nasa hondureña para el fortalecimiento de la pesca artesanal

El presente trabajo es el resultado de un proceso articulado de investigación e innovación en el que se vincula la Universidad Simón Bolívar, el Sector Productivo a través de asociaciones de pescadores del departamento del Atlántico, y el Estado a través del Ministerio de Agricultura. Se fundamentó en la imperiosa necesidad del sector pesquero de diversificar su actividad y fortalecer sus procesos internos en aras de hacerse más competitivo y sostenible. En este sentido, se soportó en la generación de nuevo conocimiento, la transferencia de tecnologías, la capacitación, la asistencia técnica y la validación técnica y económica de un arte de pesca nuevo en la región como estrategias de fortalecimiento empresarial de organizaciones del sector primario.This work is a result from a research and innovation process jointly developed by the Universidad Simón Bolívar, the productive sector through fishermen partnerships of department Atlántico and the State with the Agriculture Ministry. It supported on the imperative need of the fishing industry to diversify its business and strengthen its internal processes in order to become more competitive and sustainable. In this sense, it endured in new knowledge creation, technology transfer, training, technical assistance and technical and economic validation of a new fishing art in the region as business strategies to strengthen communities in the economy primary sector

Optimal heat release shaping in a reactivity controlled compression ignition (RCCI) engine

[EN] The present paper addresses the optimal heat release (HR) law in a single cylinder engine operated under reactivity controlled compression ignition (RCCI) combustion mode to minimise the indicated specific fuel consumption (ISFC) subject to different constraints including pressure related limits (maximum cylinder pressure and maximum cylinder pressure gradient). With this aim, a 0-dimensional (0D) engine combustion model has been identified with experimental data. Then, the optimal control problem of minimising the ISFC of the engine at different operating conditions of the engine operating map has been stated and analytically solved. To evaluate the method viability a data-driven model is developed to obtain the control actions (gasoline fraction) leading to the calculated optimal HR, more precisely to the optimal ratio between premixed and diffusive combustion. The experimental results obtained with such controls and the differences with the optimal HR are finally explained and discussed.This work was supported by Ministerio de Economía y Competitividad through Project TRA2016-78717-R.Guardiola, C.; Plá Moreno, B.; García Martínez, A.; Boronat-Colomer, V. (2017). Optimal heat release shaping in a reactivity controlled compression ignition (RCCI) engine. Control Theory and Technology. 15(2):117-128. https://doi.org/10.1007/s11768-017-6155-5S117128152F. Payri, J. M. Luján, C. Guardiola, et al. A challenging future for the IC engine: New technologies and the control role. Oil & Gas Science and Technology–Revue D IFP Energies Nouvelles, 2015, 70(1): 15–30.H. Yanagihara, Y. Sato, J. Minuta. A simultaneous reduction in NOx and soot in diesel engines under a new combustion system (Uniform Bulky Combustion System–UNIBUS). Proceedings of the 17th international Vienna Motor Symposium, Vienna, 1996: 303–314.D. A. Splitter, M. L. Wissink, T. L. Hendricks, et al. Comparison of RCCI, HCCI, and CDC operation from low to full load. THIESEL 2012 conference on thermo-and fluid dynamic processes in direct injection engines. Valencia, 2012.J. Benajes, J. V. Pastor, A. García, et al. The potential of RCCI concept to meet EURO VI NOx limitation and ultra-low soot emissions in a heavy-duty engine over the whole engine map. Fuel, 2015, 159(1): 952–961.J. Benajes, A. García, J. Monsalve-Serrano, et al. An assessment of the dual-mode reactivity controlled compression ignition/conventional diesel combustion capabilities in a EURO VI medium-duty diesel engine fueled with an intermediate ethanol-gasoline blend and biodiesel. Energy Conversion and Management, 2016, 123(1): 381–391.S. Molina, A. García, J. M. Pastor, et al. Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine. Applied Energy, 2015, 143: 211–227.D. A. Splitter, R. D. Reitz. Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines. Fuel, 2014, 118(5): 163–175.J. Benajes, S. Molina, A. García, et al. Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine. Energy, 2015, 90: 1261–1271.J. Benajes, S. Molina, A. García, et al. An investigation on RCCI combustion in a heavy duty diesel engine using incylinder blending of diesel and gasoline fuels. Applied Thermal Engineering, 2014, 63(1): 66–76.J. Li, W. M. Yang, H. An, et al. Numerical investigation on the effect of reactivity gradient in an RCCI engine fueled with gasoline and diesel. Energy Conversion and Management, 2015, 92(1): 342–352.J. Benajes, S. Molina, A. García, et al. Effects of direct injection timing and blending ratio on RCCI combustion with different low reactivity fuels. Energy Conversion and Management, 2015, 99(1): 193–209.J. Benajes, J. V. Pastor, A. García, et al. A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio. Energy Conversion and Management, 2016, 126(1): 497–508.F. Zurbriggen, T. Ott, C. Onder, et al. Optimal control of the heat release rate of an internal combustion engine with pressure gradient, maximum pressure, and knock constraints. Journal of Dynamic Systems, Measurement, and Control, 2014, 136(6): DOI 10.1115/1.4027592.L. Eriksson, M. Sivertsson. Computing optimal heat release rates in combustion engines. SAE International Journal of Engines, 2015, 8(3): 1069–1079.L. Eriksson, M. Sivertsson. Calculation of optimal heat release rates under constrained conditions. SAE International Journal of Engines, 2016, 9(2): 1143–1162.Y. Zhang, T. Shen. Model based combustion phase optimization in SI engines: Variational analysis and spark advance determination. IFAC-PapersOnLine, 2016, 49(11): 679–684.F. Payri, P. Olmeda, J. Martín, et al. A new tool to perform global energy balances in DI diesel engines. SAE International Journal of Engines, 2014, 7(7): 43–59.S. Yu, M. Zheng. Ethanol-diesel premixed charge compression ignition to achieve clean combustion under high loads. Proceedings of the Institution of Mechanical Engineers–Part D: Journal of Automobile Engineering, 2016, 30(4): 527–541.D. Klos, D. Janecek, S. Kokjohn. Investigation of the combustion instability-NOx tradeoff in a dual fuel reactivity controlled compression ignition (RCCI) engine. SAE International Journal of Engines, 2015, 8(2): 821–830.G. Woschni. A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine. SAE Technical Paper. 1967: DOI 10.4271/670931.C. Guardiola, J. López, J. Martín, et al. Semi-empirical in-cylinder pressure based model for NOx prediction oriented to control applications. Applied Thermal Engineering, 2011, 31(16): 3275–3286.C. Guardiola, J. Martín, B. Pla, et al. Cycle by cycle NOx model for diesel engine control. Applied Thermal Engineering, 2017, 110: 1011–1020.J. M. Desantes, J. J. López, P. Redón, et al. Evaluation of the Thermal NO formation mechanism under low temperature diesel combustion conditions. International Journal of Engine Research, 2012, 13(6): 531–539.O. Sundstrm, L. Guzzella. A generic dynamic programming Matlab function. IEEE International Conference on Control Applications/International Symposium on Intelligent Control, St Petersburg: IEEE, 2009: 1625–1630.J. Benajes, A. García, J. M. Pastor, et al. Effects of piston bowl geometry on reactivity controlled compression ignition heat transfer and combustion losses at different engine loads. Fuel, 2016, 98(1): 64–77.J. Benajes, J. V. Pastor, A. García, et al. An experimental investigation on the influence of piston bowl geometry on RCCI performance and emissions in a heavy-duty engine. Energy Conversion and Management, 2015, 103: 1019–1031.J. M. Desantes, J. Benajes, A. García, et al. The role of the incylinder gas temperature and oxygen concentration over low load RCCI combustion efficiency. Energy, 2014, 78(SI): 854–868

Ground state of N=Z doubly closed shell nuclei in CBF theory

The ground state properties of N=Z doubly closed shell nuclei are studied within correlated basis function theory. A truncated version of the Urbana v14 realistic potential, with spin, isospin and tensor components, is adopted, together with state dependent correlations. Fermi hypernetted chain integral equation and single operator chain approximation are used to evaluate density, distribution function and ground state energy of 16O and 40Ca. The results favourably compare with the available, variational MonteCarlo estimates and provide a first substantial check of the accuracy of the cluster summation method for state dependent correlations. We achieve in finite nuclei at least the same level of accuracy in the treatment of non central interactions and correlations as in nuclear matter. This opens the way for a microscopic study of medium heavy nuclei ground state using present days realistic hamiltonians.Comment: 35 pages (LateX) + 3 figures. Phys.Rev.C, in pres