A recipe for an unpredictable random number generator

In this work we present a model for computation of random processes in digital computers which solves the problem of periodic sequences and hidden errors produced by correlations. We show that systems with non-invertible non-linearities can produce unpredictable sequences of independent random numbers. We illustrate our result with some numerical calculations related with random walks simulations.Comment: 8 pages, 5 figures, Proceedings Mochima spring school in theoretial physic

Tlatoani Cuauhtemoczin, el barrio de Analco, y la Mexicanidad La Conformidad de Danza Azteca-Chichimeca de Conquista

In 1521 the Mexica-Tenochca people from Mexico-Tenochtitlan took their last stand against the invasion of the Spanish army and their native allies. The story tells us that during this confrontation the Tlatoani Cuauhtemoczin addressed the people and gave them their last command. He told them that “our sun has concealed itself. Our sun has hidden itself and has left us in darkness. However, we know that it will return. It will come forth again and once again give us light. But while it remains in the house of resting and transformation, we should unite, concealing deep within our hearts all that we love” and “let the fathers and mothers become the teachers and guides that will lead their children while they live.” After addressing his people for the last time, the Tlatoani Cuauhtemoczin met Hernan Cortez with dignity for his duty to protect his people had ended. At that very moment a new chapter in the history of Anahuac2 had begun. At that precise moment of confrontation between the young leader and the Spaniard a new Mexicanidad3 emerged. This new Mexicanidad meant a religious syncretism that intended to safe guard the spiritual beliefs of the Mexica people by ingraining them into the beliefs of the Catholic Church

Partial Differential Equations in Curved Spacetimes

It is the ambition of this thesis to analyze in a concise and coherent manner the idiosyncratic nature of partial differential equations and their mathematical structure in distinct curved spacetimes. In our work special interest is taken in quantum fields dwelling within the de-Sitter geometry. In Chapters I, II, III, and IV, a meticulous study of general relativity is undertaken with one of its solutions derived, an introduction of quantum mechanics is posed, the relativistic quantum theory of fermions is defined, and a “merging” of the former chapters and results are considered, respectively. With what has been derived we seek to examine the paradigm of the Dirac equation in the de-Sitter spacetime. We determine the vierbein, its dual, and the spin connection of the metric under consideration in order to define the Dirac equation in the de Sitter geometry. Once achieved we seek to redefine the former in Klein-Gordon form such that we may derive an analytic solution to the novel equation. Inevitably, the physical ramifications of said solution will detail the behavior of a relativistic fermion traversing through the de Sitter geometry

Universal functions and exactly solvable chaotic systems

A universal differential equation is a nontrivial differential equation the solutions of which approximate to arbitrary accuracy any continuous function on any interval of the real line. On the other hand, there has been much interest in exactly solvable chaotic maps. An important problem is to generalize these results to continuous systems. Theoretical analysis would allow us to prove theorems about these systems and predict new phenomena. In the present paper we discuss the concept of universal functions and their relevance to the theory of universal differential equations. We present a connection between universal functions and solutions to chaotic systems. We will show the statistical independence between $X(t)$ and $X(t + \tau)$ (when $\tau$ is not equal to zero) and $X(t)$ is a solution to some chaotic systems. We will construct universal functions that behave as delta-correlated noise. We will construct universal dynamical systems with truly noisy solutions. We will discuss physically realizable dynamical systems with universal-like properties.Comment: 12 Pages, 9 figures. Proceedings 1st Meeting IST-IM

Ambulatory EMR Adoption in the USA: A Longitudinal Study

Based on a longitudinal national survey, this study examines the adoption of electronic medical records (EMR) by clinics in the USA between 2004 and 2014. A trend analysis suggests that government incentive, technological breakthrough and patient-centered care push the diffusion forward. The interaction among policy, technology and practice is likely to affect the decision-making of practitioners regarding EMR adoption. This study identifies clinic-, patient- and visit-related variables from the survey, and uses them to predict EMR adoption intention and usage in each year. The explanatory power of different variables changed over time in different ways, revealing how policy, technology, and practice influence EMR adoption together. The findings yield implications for the strategies and best practices of health IT diffusion

Validation and Analysis of Heat Losses Prediction Using Conjugate Heat Transfer Simulation for an Internal Combustion Engine

[EN] New technologies are required to improve engine thermal efficiency. For this it is necessary to use all the tools available nowadays, in particular computational tools, which allow testing the viability of different solutions at reduced cost. In addition, numerical simulations often provide more complete and precise information than experimental tests. Such is the case for the study of the heat transfer through the walls of an engine. Conjugate Heat Transfer (CHT) simulations permit precise calculations of the heat transfer rate from gas to walls throughout the whole engine cycle, and thus it is possible to know such details as the instantaneous heat losses and wall temperature distribution on the walls, which no experiment can give. Nevertheless, it is important to validate CHT calculations, either with some experimental measurements or with some other reliable tool, such as 0D-1D modelling known to work well. The proposed work is based on the CHT simulation of the heat transfer to the walls of an engine piston during an entire cycle to determine the parameters that permit obtaining good results. This will be ascertained by comparison with the results of a lumped model previously validated for many applications. Another objective of this work is also to determine if it is significant to take into account the spatial and temporal variations of the wall temperature for the prediction of the heat losses during the engine cycle, as generally a mean and constant wall temperature (isothermal walls) is assumed for CFD combustion calculations.This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 724084. The authors wish to thank IFPEN for their permission to use their single cylinder engine geometry and pressure results. The authors want to express their gratitude to CONVERGENT SCIENCE Inc. and Convergent Science GmbH for their kind support for performing the CFD-CHT calculations using CONVERGE software.Broatch, A.; Margot, X.; Garcia Tiscar, J.; Escalona, J. (2019). Validation and Analysis of Heat Losses Prediction Using Conjugate Heat Transfer Simulation for an Internal Combustion Engine. SAE International. 1-8. https://doi.org/10.4271/2019-24-009118Leguille, M., Ravet, F., Le Moine, J., Pomraning, E. et al. , “Coupled Fluid-Solid Simulation for the Prediction of Gas-Exposed Surface Temperature Distribution in a SI Engine,” SAE Technical Paper 2011-24-0132 , 2011, doi:104271/2011-24-0132.Mohammadi, A. and Yaghoubi, M. , “Estimation of Instantaneous Local Heat Transfer Coefficient in Spark-Ignition Engines,” International Journal of Thermal Sciences 49(7):1309-1317, 2010.Babajimopoulos, A., Assanis, D.N., Flowers, D.L., Aceves, S. M., and Hessel, R.P. , “A Fully Coupled Computational Fluid Dynamics and Multi-Zone Model with Detailed Chemical Kinetics for the Simulation of Premixed Charge Compression Ignition Engines,” International Journal of Engine Research 6(5):497-512, 2005.Fischer, M. and Jiang, X. , “Numerical Optimisation for Model Evaluation in Combustion Kinetics,” Applied Energy 156:793-803, 2015.Xin, J., Shih, S., Itano, E., and Maeda, Y. , “Integration of 3D Combustion Simulations and Conjugate Heat Transfer Analysis to Quantitatively Evaluate Component Temperatures,” SAE Technical Paper 2003-01-3128 , 2003, doi:10.4271/2003-01-3128.Iqbal, O., Arora, K., and Sanka, M. , “Thermal Map of an IC Engine Via Conjugate Heat Transfer: Validation and Test Data Correlation,” SAE International Journal of Engines 7(1):366-374, 2014.Lee, S. and Bae, C. , “Design of a Heat Exchanger to Reduce the Exhaust Temperature in a Spark-Ignition Engine,” International Journal of Thermal Sciences 47(4):468-478, 2008.Kashdan, J. and Bruneaux, G. , “Laser-Induced Phosphorenscence of Combustion Chamber Surface Temperature on a Single-Cylinder Diesel Engine,” SAE Technical Paper 2011-01-2049 , 2011, doi:10.4271/2011-01-2049.Knappe, C., Algotsson, M., Andersson, P., Richter, M. et al. , “Thickness Dependent Variations in Surface Phosphor Thermometry during Transient Combustion in an HCCI Engine,” Combustion and Flame 160(8):1466-1475, 2013.Torregrosa, A.J., Olmeda, P., Degraeuwe, B., and Reyes, M. , “A Concise Wall Temperature Model for Di Diesel Engines,” Applied Thermal Engineering 26(11-12):1320-1327, 2006.Torregrosa, A.J., Olmeda, P., Martín, J., and Romero, C. , “A Tool for Predicting the Thermal Performance of a Diesel Engine,” Heat Transfer Engineering 32(10):891-904, 2011.Kundu, P., Scarcelli, R., Som, S., Ickes, A. et al. , “Modeling Heat Loss through Pistons and Effect of Thermal Boundary Coatings in Diesel Engine Simulations Using a Conjugate Heat Transfer Model,” SAE Technical Paper 2016-01-2235 , 2016, doi:10.4271/2016-01-2235.Senecal, P.K., Pomraning, E., Anders, J., Weber, M. et al. , “Predictions of Transient Flame Lift-Off Length with Comparison to Single-Cylinder Optical Engine Experiments,” Journal of Engineering for Gas Turbines and Power 136(11):111505, 2014.Som, S., Longman, D., Aithal, S., Bair, R. et al. , “A Numerical Investigation on Scalability and Grid Convergence of Internal Combustion Engine Simulations,” SAE Technical Paper 2013-01-1095 , 2013, doi:10.4271/2013-01-1095.Pei, Y., Shan, R., Som, S., Lu, T. et al. , “Global Sensitivity Analysis of a Diesel Engine Simulation with Multi-Target Functions,” SAE Technical Paper 2014-01-1117 , 2014, doi:10.4271/2014-01-1117.Andruskiewicz, P., Najt, P., Durrett, R., Biesboer, S. et al. , “Analysis of the Effects of Wall Temperature Swing on Reciprocating Internal Combustion Engine Processes,” International Journal of Engine Research 19(4):461-473, 2018.Woschni, G., Spindler, W., and Kolesa, K. , “Heat Insulation of Combustion Chamber Walls-A Measure to Decrease the Fuel Consumption of IC Engines?” SAE Technical Paper 870339 , 1987, doi:10.4271/870339.Kosaka, H., Wakisaka, Y., Nomura, Y., Hotta, Y. et al. , “Concept of “Temperature Swing Heat Insulation” in Combustion Chamber Walls, and Appropriate Thermo-Physical Properties for Heat Insulation Coat,” SAE International Journal of Engines 6(1):142-149, 2013.Fukui, K., Wakisaka, Y., Nishikawa, K., Hattori, Y. et al. , “Development of Instantaneous Temperature Measurement Technique for Combustion Chamber Surface and Verification of Temperature Swing Concept,” SAE 2016 World Congress and Exhibition, SAE International, 2016.Hartmann, F., Buhl, S., Hasse, C., Krost, P., Henke, M., and Hübner, W. , “Erschließung von wirkungsgradpotentialen durch reduzierung der wärmeverluste mittels innovativer kolbenbeschichtungen,” in 16th Conference, The Working Process of the Internal Combustion Engines, Graz, September 2017.Broatch, A., Olmeda, P., Margot, X., and Gomez-Soriano, J. , “Numerical Simulations for Evaluating the Impact of Advanced Insulation Coatings on H2 Additivated Gasoline Lean Combustion in a Turbocharged Spark-Ignited Engine,” Applied Thermal Engineering 148:674-683, 2019.Broatch, A., Olmeda, P., Margot, X., and Escalona, J. , “New Approach to Study the Heat Transfer in Internal Combustion Engines by 3D Modelling,” International Journal of Thermal Sciences 138:405-415, 2018.Wiedenhoefer, J.F. and Reitz, R.D. , “A Multidimensional Radiation Model for Diesel Engine Simulation with Comparison to Experiment,” Numerical Heat Transfer Part A 44(7):665-682, 2003.Urip, E., Liew, K.H., and Yang, S.L. , “Modeling IC Engine Conjugate Heat Transfer Using the KIVA Code,” Numerical Heat Transfer, Part A: Applications 52(1):1-23, 2007.Li, Y. and Kong, S.-C. , “Coupling Conjugate Heat Transfer with In-Cylinder Combustion Modeling for Engine Simulation,” International Journal of Heat and Mass Transfer 54(11):2467-2478, 2011.Patil, M.M., Pise, A., and Gokhale, N. , “Simulation of Conjugate Heat Transfer (CHT) between Engine Head and Cooling Medium of Diesel Engine,” SAE Technical Paper 2015-01-1662 , 2015, doi:10.4271/2015-01-1662.Bejan, A. and Kraus, A.D. , Heat Transfer Handbook. Vol. 1 (John Wiley & Sons, 2003).Broatch, A., Margot, X., Novella, R., and Gomez-Soriano, J. , “Impact of the Injector Design on the Combustion Noise of Gasoline Partially Premixed Combustion in a 2-Stroke Engine,” Applied Thermal Engineering 119:530-540, 2017.Convergent Science Inc. , CONVERGE 2.2 Theory Manual.O’Rourke, P. and Amsden, A.A. , “A Particle Numerical Model for Wall Film Dynamics in Port-Injected Engines,” SAE Technical Paper 961961 , 1996, doi:10.4271961961.Amsden, A. , “KIVA-3V: A Block-Structured KIVA Program for Engines with Vertical or Canted Valves,” Los Alamos, National Laboratory, 1997.Torregrosa, A.J., Broatch, A., Olmeda, P., and Martín, J. , “A Contribution to Film Coefficient Estimation in Piston Cooling Galleries,” Experimental Thermal and Fluid Science 34(2):142-151, 2010.Olmeda, P., Dolz, V., Arnau, F., and Reyes-Belmonte, M. , “Determination of Heat Flows inside Turbochargers by Means of a One Dimensional Lumped Model,” Mathematical and Computer Modelling 57(7-8):1847-1852, 2013.Broatch, A., Olmeda, P., García, A., Salvador-Iborra, J., and Warey, A. , “Impact of Swirl on In-Cylinder Heat Transfer in a Light-Duty Diesel Engine,” Energy 119:1010-1023, 2017.Kikusato, A., Terahata, K., Jin, K., and Daisho, Y. , “A Numerical Simulation Study on Improving the Thermal Efficiency of a Spark Ignited Engine---Part 2: Predicting Instantaneous Combustion Chamber Wall Temperatures, Heat Losses and Knock,” SAE International Journal of Engines 7(1):87-95, 2014

Probing strong dynamics with cosmic neutrinos

IceCube has observed 80 astrophysical neutrino candidates in the energy range 0.02 Eν/PeV2. Deep inelastic scattering of these neutrinos with nucleons on Antarctic ice sheet probe center-of-mass energies s∼1 TeV. By comparing the rates for two classes of observable events, any departure from the benchmark (perturbative QCD) neutrino-nucleon cross section can be constrained. Using the projected sensitivity of South Pole next-generation neutrino telescope we show that this facility will provide a unique probe of strong interaction dynamics. In particular, we demonstrate that the high-energy high-statistics data sample to be recorded by IceCube-Gen2 in the very near future will deliver a direct measurement of the neutrino-nucleon cross section at s∼1 TeV, with a precision comparable to perturbative QCD informed by HERA data. We also use IceCube data to extract the neutrino-nucleon cross section at s∼1 TeV through a likelihood analysis, considering (for the first time) both the charged-current and neutral-current contributions as free parameters of the likelihood function.Fil: Anchordoqui, Luis A.. American Museum of Natural History; Estados Unidos. City University of New York; Estados UnidosFil: Garcia Canal, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Soriano, Jorge F.. City University of New York; Estados Unido

On the influence of inlet elbow radius on recirculating backflow, whoosh noise and efficiency in turbocharger compressors

[EN] While the influence of inlet geometry on turbocharger compressor behaviour has usually been investigated in terms of performance, surge margin and efficiency, data is scarce regarding the impact of the inlet flow field onto the noise emission. In many applications where tight packaging is required, a 90° elbow is placed just upstream of the compressor inducer. This can create a distortion of the incoming flow that affects the turbocharger operation; a distortion that is related to the radius of the elbow. In this experimental investigation three 90° elbow inlets are tested, measuring the in-duct sound intensity through acoustic beamforming, the spectral signature of the noise, and the distortion of the high temperature backflow typical of partially stalled conditions by means of thermocouple arrays. Results show that a tighter elbow radius not only impacts efficiency but also increases inlet noise at conditions close to surge. Spectral analysis shows that this increase is mainly produced in the form of a medium frequency broadband noise usually known as `whoosh¿ in the literature. On the other hand, effect on the outlet is less noticeable. Measurements of the recirculated backflow distortion in terms of circumferential skewness show good correlation with whoosh noise increase, indicating that flow distortion caused by tighter elbows at marginal surge conditions facilitates the transmission of whoosh noise oscillations to the inlet duct, worsening the acoustic behaviour of the system.The equipment used in this work has been partially supported by the Spanish Ministerio de Economia y Competitividad through grant DPI2015-70464-R and by FEDER project funds 'Dotacion 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. F. Roig is partially supported through the Programa de Apoyo para la Investigacion y Desarrollo of Universitat Politecnica de Valencia (PAID-01-17).Broatch, A.; Ruiz, S.; Garcia Tiscar, J.; Roig-Villanueva, F. (2018). On the influence of inlet elbow radius on recirculating backflow, whoosh noise and efficiency in turbocharger compressors. Experimental Thermal and Fluid Science. 96:224-233. https://doi.org/10.1016/j.expthermflusci.2018.03.011S2242339

Numerical analysis of combustion noise in an atmospheric swirl-stabilized LDI burner through modal decomposition techniques

[EN] Combustion noise in gas turbine engines has recently become a relevant source of noise in the aircraft due to the appearance of new burner architectures that are intrinsically more unstable, and the optimization of other conventional noise sources in this mean of transport (e.g., jet, fan, airframe). In this work, a simulation setup for reactive conditions was prepared in the CONVERGE finite-volume package using the detailed chemistry SAGE solver to model the combustion of a benchmark case, which was solved using a LES approach with three different cell base sizes: 8,10,12 mm. A confined liquid-fueled swirl-stabilized burner located at the CORIA Laboratory, France, was used to validate the numerical results with the experimental measurements obtained at this facility. OH-PLIF measurements and PDA results for both phases were used to guarantee the accuracy of the numerical OH contours and the velocity profiles of both phases. These experimental measurements were collected at CORIA. After ensuring the stabilization of the numerical flame, the reactive simulations were extended with some adjustments in the time step to capture the acoustic motion. Several techniques like Fast Fourier Transform (FFT), Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) were used to analyze these results and confirm the presence of a Precessing Vortex Core (PVC) and a Vortex Breakdown Bubble (VBB) during the coupling of pressure, axial velocity and fuel mass fraction in reactive conditions. Furthermore, the acoustic analysis performed with a Helmholtz solver proved that the second longitudinal mode of the chamber (329 Hz) was present in the pressure signal (300 Hz in the LES calculations) and resonated with the Vortex Breakdown Bubble (VBB). However, this dominant frequency did not appear in the frequency distribution of the OH mass fraction and no feedback interaction between the acoustic and the combustion happened. Thus, only combustion noise was obtained.This work was supported by the institutional program of the Korea Institute of Science and Technology (KIST, Project No. 2E32582).Broatch, A.; Carreres, M.; Garcia Tiscar, J.; Rodríguez-Pastor, M. (2023). Numerical analysis of combustion noise in an atmospheric swirl-stabilized LDI burner through modal decomposition techniques. Aerospace Science and Technology. 137:1-17. https://doi.org/10.1016/j.ast.2023.10828111713