Modelo numérico para el estudio dinámico de un rotor con eje agrietado

En este trabajo se presenta un análisis teórico de la dinámica de un sistema rotor-descansos con una grieta transversal en su eje. Con el objeto de poder utilizar programas estándares de elementos finitos se deduce utilizando los principios de la mecánica de fractura, la matriz de rigidez para un elemento de eje con una grieta transversal que se abre y cierra. Los cambios de rigidez generados por el respiro de la grieta son expresados a través de una función armónica. Se analiza la influencia de la grieta en las vibraciones transversales y longitudinales de un rotor sencillo perfectamente balanceado. Los resultados obtenidos son comparados con resultados de trabajos teóricos y experimentales publicados anteriormente. Se muestra cómo las componentes espectrales de los desplazamientos vibratorios 1 0, 2 R y 3 R varían con la velocidad del rotor. Esto es un buen indicador a usar para diagnosticar un eje agrietado en los sistemas de monitoreo de vibraciones.A theoretical analysis of the dynamics of a rotor-bearing system with a transversely cracked shaft is presented. In order to model the system for standard finite element method, the stiffness matrix of a shaft element with an opening/closing crack is derived based on fracture mechanics. The change of stiffness due to the crack breathing is expressed through an harmonica function. The influence of crack on the transversal and longitudinal vibration of a simple balanced rotor is analyzed. Results obtained by this analysis procedure are compared with previous analytical and experimental works published. From the FFT analysis of the displacement responses, it is shown how the 1 R, 2 R and 3 R components excited varied with speed rotor. This provides good indicator for diagnosing a cracked shaft from a vibration monitoring system.Peer Reviewe

Analytical method for perturbed frozen orbit around an Asteroid in highly inhomogeneous gravitational fields : A first approach

This article provides a method for nding initial conditions for perturbed frozen orbits around inhomogeneous fast rotating asteroids. These orbits can be used as reference trajectories in missions that require close inspection of any rigid body. The generalized perturbative procedure followed exploits the analytical methods of relegation of the argument of node and Delaunay normalisation to arbitrary order. These analytical methods are extremely powerful but highly computational. The gravitational potential of the heterogeneous body is rstly stated, in polar-nodal coordinates, which takes into account the coecients of the spherical harmonics up to an arbitrary order. Through the relegation of the argument of node and the Delaunay normalization, a series of canonical transformations of coordinates is found, which reduces the Hamiltonian describing the system to a integrable, two degrees of freedom Hamiltonian plus a truncated reminder of higher order. Setting eccentricity, argument of pericenter and inclination of the orbit of the truncated system to be constant, initial conditions are found, which evolve into frozen orbits for the truncated system. Using the same initial conditions yields perturbed frozen orbits for the full system, whose perturbation decreases with the consideration of arbitrary homologic equations in the relegation and normalization procedures. Such procedure can be automated for the first homologic equation up to the consideration of any arbitrary number of spherical harmonics coefficients. The project has been developed in collaboration with the European Space Agency (ESA)

Entropy, Topological Theories and Emergent Quantum Mechanics

[EN] The classical thermostatics of equilibrium processes is shown to possess a quantum mechanical dual theory with a finite dimensional Hilbert space of quantum states. Specifically, the kernel of a certain Hamiltonian operator becomes the Hilbert space of quasistatic quantum mechanics. The relation of thermostatics to topological field theory is also discussed in the context of the approach of the emergence of quantum theory, where the concept of entropy plays a key role.Research supported by grant No. ENE2015-71333-R (Spain).Cabrera, D.; Fernández De Córdoba Castellá, PJ.; Isidro San Juan, JM.; Vazquez Molina, J. (2017). Entropy, Topological Theories and Emergent Quantum Mechanics. Entropy. 19(3). https://doi.org/10.3390/e19030087S19

THE ROLE OF CHOLINESTERASES IN ALZHEIMER’S DISEASE: SCREENING OF TARGET COMPOUNDS

Background: Alzheimer's disease (AD) is the most common form of dementia and causes a progressive and irreversible neurodegeneration. The loss of cholinergic neurons leads to the progressive reduction of acetylcholine (ACh) in the brain and resulting cognitive impairment in AD. ACh is hydrolyzed by both acetylcholinesterase (AChE) and butirylcholinesterase (BuChE). It was found that in the course of the disease, levels of AChE in the central nervous system (CNS) decrease, inversely to BuChE levels, so both enzymes represent legitimate therapeutic targets for ameliorating the cholinergic deficit characteristic of AD. Objective: Screen a library of new isoquinoline, indolinone and benzoazepinone derivatives for their ability to inhibit AChE and BuChE activities, using galantamine and rivastigmine as standards. Methods: The enzyme activities and inhibition studies were carried out using spectrophotometric techniques, based on the Ellman’s method, with acetylthiocholine (ATCI) and butirylthiocholine (BTCI) as substrates, for AChE and BuChE, respectively. The data were complemented with modeling to analyze the structure-activity relationship. Results: Our results show that the tested compounds are competitive inhibitors for AChEs and BuChEs, as the benchmarks galantamine and rivastigmine. The isoquinoline and indolinone derivative compounds showed strong anti-cholinesterases activities, with IC50 values ranging from 0.4 to 400 micromolar. Conclusions: The results presented are promising and provide a pathway for the design of new AChE and BuChE inhibitors

Low precision matrix multiplication for efficient deep learning in NVIDIA Carmel processors

[EN] We introduce a high performance, multi-threaded realization of the gemm kernel for the ARMv8.2 architecture that operates with 16-bit (half precision)/queryKindly check and confirm whether the corresponding author is correctly identified. floating point operands. Our code is especially designed for efficient machine learning inference (and to a certain extent, also training) with deep neural networks. The results on the NVIDIA Carmel multicore processor, which implements the ARMv8.2 architecture, show considerable performance gains for the gemm kernel, close to the theoretical peak acceleration that could be expected when moving from 32-bit arithmetic/data to 16-bit. Combined with the type of convolution operator arising in convolutional neural networks, the speed-ups are more modest though still relevant.This work was supported by projects TIN2017-82972-R and RTI2018-093684-B-I00 from the Ministerio de Ciencia, Innovacion y Universidades, project S2018/TCS-4423 of the Comunidad de Madrid, project PR65/19-22445 of the UCM, and project Prometeo/2019/109 of the Generalitat Valenciana.San Juan-Sebastian, P.; Rodríguez-Sánchez, R.; Igual, FD.; Alonso-Jordá, P.; Quintana-Ortí, ES. (2021). Low precision matrix multiplication for efficient deep learning in NVIDIA Carmel processors. The Journal of Supercomputing. 77(10):11257-11269. https://doi.org/10.1007/s11227-021-03636-41125711269771