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

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

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 Design of Heat Exchangers for Altitude Simulators

[EN] Altitude simulators for internal combustion engines are broadly used in order to simulate different atmospheric pressure and temperatures on a test bench. One of the main problems of these devices is their outlet temperature and in order to control it, at least one heat exchanger is needed. A methodology to define, select and analyses the best heat exchanger that fulfill the requirements is presented. The methodology combines CFD and 0D models with experimental test. The combination of these tools allows to adjust both the 0D and the CFD models. The adjusted 0D model will be used to perform parametric analysis that will help to select the best geometrical combinations considering heat transfer and pressure losses while the CFD model will help to find possible local deficiencies on the designed Heat Exchanger and, therefore, try to improve it. Finally, the adjusted 0D model have been used to perform parametric studies changing the most important geometric characteristics to analyze the effect on HEX performance.Broatch, A.; Olmeda, P.; Garcia Tiscar, J.; Roig-Villanueva, F. (2021). On the Design of Heat Exchangers for Altitude Simulators. SAE International. 1-12. https://doi.org/10.4271/2021-01-038811

Dynamic mode decomposition of the acoustic field in radial compressors

[EN] Widely recognized since the beginning of air travel as a major issue, noise reduction remains nowadays a pressing concern for all stakeholders in the aviation industry. While aeroengine compressors, specially at the approach phase, have been historically identified as a leading source of noise, most of the research has been conducted on compressors of the axial type. However, radial compressors are found in a wide array of applications: smaller business jets, helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers for reciprocating engines, etc. Owing to their geometrical particularities, radial compressors feature flow patterns that differ from their axial counterparts, leading to different acoustic performance but also opening the door for different optimization approaches. Yet, classical modal decomposition techniques focused on duct propagation may fail to reveal the complex interactions between geometry and flow features that act as noise sources. In this paper we apply, in addition to the classical approach, a data-driven Dynamic Mode Decomposition (DMD) to pressure data coming from a Detached Eddy Simulation (DES), in which we have experimentally validated the correct reproduction of the modal behaviour of the compressor, thus obtaining in-depth details of the link between flow phenomena and noise generation and transmission across the inlet and outlet ducts. (C) 2019 Elsevier Masson SAS. All rights reserved.The equipment used in this work has been partially supported by the Spanish Ministerio de Economía y Competitividad through grant [DPI2015-70464-R] and by FEDER project funds Dotación de infraestructuras científico técnicas para el Centro Integral de Mejora Energética y Medioambiental de Sistemas de Transporte (CiMeT), [FEDER-ICTS-2012-06] framed in the operational program of unique scientific and technical infrastructure of the Spanish Ministerio de Economía y Competitividad. F. Roig is supported through the Programa de Apoyo para la Investigación y Desarrollo of the Universitat Politècnica de València [PAID-01-17].Broatch, A.; Garcia Tiscar, J.; Roig-Villanueva, F.; Sharma, S. (2019). Dynamic mode decomposition of the acoustic field in radial compressors. Aerospace Science and Technology. 90:388-400. https://doi.org/10.1016/j.ast.2019.05.015S3884009