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This paper deals with acoustic gunshot detectionfrom small arms primarily for use in urban areas. Key part of thepaper is an examination of typical features of gunshot signals.Based on the short-term features detection algorithms areproposed in the time and frequency domains. Training andevaluation of the algorithms was performed using real gunshots,non-gunshots as well as synthetic gunshots. The non-gunshots setcontains impulsive acoustic events such as dog barking, glassbreaking, car horn, etc.

This paper deals with acoustic gunshot detectionfrom small arms primarily for use in urban areas. Key part of thepaper is an examination of typical features of gunshot signals.Based on the short-term features detection algorithms areproposed in the time and frequency domains. Training andevaluation of the algorithms was performed using real gunshots,non-gunshots as well as synthetic gunshots. The non-gunshots setcontains impulsive acoustic events such as dog barking, glassbreaking, car horn, etc.

The paper presents an iterative procedure for the time domain deconvolution in nonlinear elastoplastic materials. The approach is intended for the generation of input motions for dynamic soil–structure interaction (DSSI) numerical analyses when the desired earthquake is specified at the surface of a nonlinear soil deposit. The main advantage is that the same constitutive model (or models) to be used in the DSSI simulation to characterise the soil deposit is also employed in the deconvolution procedure. Therefore, the desired surface motion is recovered from the free-field propagation of the resulting input motion at the base of the numerical model, accounting for the assumed constitutive behaviour of the ground. An application example is also presented, where the potential of the proposed approach is shown., Peer Reviewed, Postprint (published version)

This paper deals with acoustic gunshot detectionfrom small arms primarily for use in urban areas. Key part of thepaper is an examination of typical features of gunshot signals.Based on the short-term features detection algorithms areproposed in the time and frequency domains. Training andevaluation of the algorithms was performed using real gunshots,non-gunshots as well as synthetic gunshots. The non-gunshots setcontains impulsive acoustic events such as dog barking, glassbreaking, car horn, etc.

This paper deals with acoustic gunshot detectionfrom small arms primarily for use in urban areas. Key part of thepaper is an examination of typical features of gunshot signals.Based on the short-term features detection algorithms areproposed in the time and frequency domains. Training andevaluation of the algorithms was performed using real gunshots,non-gunshots as well as synthetic gunshots. The non-gunshots setcontains impulsive acoustic events such as dog barking, glassbreaking, car horn, etc.

In the last decades, nanostructures have unlocked myriads of functionalities in nanophotonics by engineering light-matter interaction beyond what is possible with conventional bulk optics. The space of parameters available for design is practically unlimited due to the large variety of optical materials and nanofabrication techniques. Thus, computational approaches are necessary to efficiently search for the optimal solutions. In this paper, we enable the free-form inverse design in 3D of linear optical materials with arbitrary dispersion and anisotropy. This is achieved by (1) deriving an analytical adjoint scheme based on the complex-conjugate pole-residue pair model in the time domain and (2) its implementation in a parallel finite-difference time-domain framework with a topology optimization routine, efficiently running on high-performance computing systems. Our method is tested on the design problem of field confinement using dispersive nanostructures. The obtained designs satisfy the fundamental curiosity of how free-form metallic and dielectric nanostructures perform when optimized in 3D, also in comparison to fabrication-constrained designs. Unconventional free-form designs revealed by computational methods, although may be challenging or unfeasible to realize with current technology, bring new insights into how light can more efficiently interact with nanostructures and provide new ideas for forward design.

In addition to a carbon-neutral vision being recognized worldwide, the utilization of wind energies via horizontal-axis wind turbines, especially in offshore areas, has been intensively investigated from an academic perspective. Numerical simulations play a significant role in the design and optimization of offshore wind turbines. The current review focuses on studies concerning the numerical simulations of offshore wind turbine dynamics, including the modelling of the aerodynamic and hydrodynamic conditions of the environment and the reduced-order modelling of the wind turbine dynamic responses. In detail, the functions and mechanisms of each module in the numerical simulation of the wind turbine dynamics are articulated, which in turn demonstrates its importance for the design of offshore wind turbines, and hence the development of the offshore wind industry. Based on this review, it is argued that the vertical variations in wind velocities, the blade element momentum theory, the wave dynamic models, and the reduced-order model for structural dynamics are the major concerns for the numerical simulation of wind turbines. Consequently, such directions should be emphasized in future studies.

Fatigue lifetime has proven to be a leading design parameter for naval vessels. In the field of fatigue analysis and design of welded joints, two overall methods are distinguished: the temporal and spectral approach. Using empirical models, the spectral approach is typically preferred due to its efficiency, even though damage estimates are conservative. With the temporal approach, nonlinear effects can be captured, providing higher accuracy at the cost of additional computation time. Within this framework, an improvement of the spectral approach was pursued, focusing on incorporating the mean stress effect. Past efforts to include mean stress corrections were continued by focusing on applying the Walker correction. Nonlinear effects on the mean stress response were investigated and were found to be quite small for the case of a pontoon vessel. This enabled the use of the still water bending moment as a single input to the spectral mean stress model. By using Walker in the spectral mean stress correction, an overall reduction of conservatism of 21% was achieved. Future research should focus on testing new wave cases, applying additional fatigue models and investigating the effects for hull shapes of naval vessels., Marine Technology

The marching-on-in-time electric field integral equation (MOT-EFIE) and the marching-on-in-time time differentiated electric field integral equation (MOT-TDEFIE) based on a Rao-Wilton-Glisson (RWG) spatial discretization. In both formulations we employ the Dirac-delta temporal testing functions, however they differ in temporal basis functions, i.e. hat and quadratic spline basis functions. These schemes suffer from the linear-in-time solution instability. We analyze the corresponding companion matrices using projection matrices and prove mathematically that each independent solenoidal current density corresponds to a Jordan block of size two. In combination with Lidskii-Vishik-Lyusternik perturbation theory we find that finite precision causes these Jordan block eigenvalues to split and this is the root cause of the instability of both schemes. The splitted eigenvalues cause solutions with exponentially increasing magnitudes that are initially observed as constant and/or linear-in-time, yet these become exponentially increasing at discrete time steps beyond the inverse square root of the error due to finite precision, i.e. approximately after one hundred million discrete time steps in double precision arithmetic. We provide numerical evidence to further illustrate these findings., The marching-on-in-time electric field integral equation (MOT-EFIE) and the marching-on-in-time time differentiated electric field integral equation (MOT-TDEFIE) based on a Rao-Wilton-Glisson (RWG) spatial discretization. In both formulations we employ the Dirac-delta temporal testing functions, however they differ in temporal basis functions, i.e. hat and quadratic spline basis functions. These schemes suffer from the linear-in-time solution instability. We analyze the corresponding companion matrices using projection matrices and prove mathematically that each independent solenoidal current density corresponds to a Jordan block of size two. In combination with Lidskii-Vishik-Lyusternik perturbation theory we find that finite precision causes these Jordan block eigenvalues to split and this is the root cause of the instability of both schemes. The splitted eigenvalues cause solutions with exponentially increasing magnitudes that are initially observed as constant and/or linear-in-time, yet these become exponentially increasing at discrete time steps beyond the inverse square root of the error due to finite precision, i.e. approximately after one hundred million discrete time steps in double precision arithmetic. We provide numerical evidence to further illustrate these findings.

Wind-assisted ships are installed with wind propulsors capable of generating thrust for aiding the propulsion of the ship, with the purpose of saving fuel by reducing the required propeller speed and thus engine power. Wind-assisted ships are becoming more common due to high fuel prices and rising environmental concerns. The subject of this thesis is wind-assisted ship maneuverability, which is a relatively new and unexplored topic. There are many factors which this study can involve, and so the goal of this thesis is to study the general behavior of wind-assisted ships during the Turning Circle and Zig-Zag standard maneuvers, and investigate in depth the effect of different control optimization schemes for the wind propulsors. This study requires building a 4 degree-of-freedom (DOF) time domain maneuvering model in which the equations of motions for a wind-assisted ship are solved and the required parameters are input in order to execute the standard maneuvers. The model includes calculation of all the major forces on the ship, including hydrodynamic forces common among maneuvering models, and with the addition of aerodynamic forces due to the wind propulsors. Once the model is built and shows sufficient accuracy, the maneuvers are simulated for a variety of wind conditions, sail configurations, and wind propulsor trim optimization schemes. The behavior of the ship due to these different conditions and the compliance with maneuvering standards are discussed. The results of the simulations show that the maneuvering behavior of the ship is indeed significantly dependant on the wind, and also how the wind propulsors are controlled. Based on the results, in general, the ship shows the behavior to turn quickly into the wind and slowly while turning against the wind. The effect this has on the maneuvers is that the Turning Circle is generally tighter when the initial turn is turning toward the wind, and larger when the ship is initially turning away from the win, Marine Technology | Ship Hydromechanics

The present work applies several advanced spectral methods to the analysis of macroeconomic fluctuations in three countries of the European Union: Italy, The Netherlands, and the United Kingdom. We focus here in particular on singular-spectrum analysis (SSA), which provides valuable spatial and frequency information of multivariate data and that goes far beyond a pure analysis in the time domain. The spectral methods discussed here are well established in the geosciences and life sciences, but not yet widespread in quantitative economics. In particular, they enable one to identify and describe nonlinear trends and dominant cycles | including seasonal and interannual components that characterize the deterministic behavior of each time series. These tools have already proven their robustness in the application on short and noisy data, and we demonstrate their usefulness in the analysis of the macroeconomic indicators of these three countries. We explore several fundamental indicators of the countries' real aggregate economy in a univariate, as well as a multivariate setting. Starting with individual single-channel analysis, we are able to identify similar spectral components among the analyzed indicators. Next, we consider combinations of indicators and countries, in order to take different effects of comovements into account. Since business cycles are cross-national phenomena, which show common characteristics across countries, our aim is to uncover hidden global behavior across the European economies. Results are compared with previous findings on the U.S. indicators (Groth et al., 2012). Finally, the analysis is extended to include several indicators from the U.S. economy, in order to examine its influence on the European market.

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., Static energy meters have shown errors beyond the standards due to conducted electromagnetic interference of pulsed currents. This was observed in several case studies and confirmed by laboratory experiments, which showed errors up to 2675%. The extent of this interference case is unknown, because there is limited information about the waveforms occurring in the real on-site scenarios. This article aims to detect critical waveforms in on-site surveyed data that have similar characteristics as the pulses that resulted in metering errors. The time-domain parameters of the laboratory experiments that show static energy meter interference are compared to the on-site waveform data using an interpolation based on an inverse weighting distance function. Using this approach, the waveform characteristics are compared, and an error is estimated. This approach was satisfactorily validated using data from validation experiments that shows a correct estimation of the actual error according to the permissible limits for energy metering for all validation indices. The performed on-site surveys show the existence of nonlinear waveforms. During the survey of three sites for ten days, 19 531 waveforms were captured, of which 14 487 indicate large nonlinearities and 379 are estimated to produce metering errors up to 925%., Peer Reviewed, Postprint (published version)

We consider the application of the WaveHoltz iteration to time-harmonic elastic wave equations with energy conserving boundary conditions. The original WaveHoltz iteration for acoustic Helmholtz problems is a fixed-point iteration that filters the solution of the wave equation with time-harmonic forcing and boundary data. As in the original WaveHoltz method, we reformulate the fixed point iteration as a positive definite linear system of equations that is iteratively solved by a Krylov method. We present two time-stepping schemes, one explicit and one (novel) implicit, which completely remove time discretization error from the WaveHoltz solution by performing a simple modification of the initial data and time-stepping scheme. Numerical experiments indicate an iteration scaling similar to that of the original WaveHoltz method, and that the convergence rate is dictated by the shortest (shear) wave speed of the problem. We additionally show that the implicit scheme can be advantageous in practice for meshes with disparate element sizes., QC 20230522

Pulsed electromagnetic (EM) field transmission through a relatively small rectangular aperture is analyzed with the aid of the Cagniard-deHoop method of moments (CdH-MoM). The classic EM scattering problem is formulated using the EM reciprocity theorem of the time-convolution type. The resulting TD reciprocity relation is then, under the assumption of piecewise-linear, space-time magnetic-current distribution over the aperture, cast analytically into the form of discrete time-convolution equations. The latter equations are subsequently solved via a stable marching-on-in-time scheme. Illustrative examples are presented and validated using a 3D numerical EM tool.

Pulsed electromagnetic (EM) field transmission through a relatively small rectangular aperture is analyzed with the aid of the Cagniard-deHoop method of moments (CdH-MoM). The classic EM scattering problem is formulated using the EM reciprocity theorem of the time-convolution type. The resulting TD reciprocity relation is then, under the assumption of piecewise-linear, space-time magnetic-current distribution over the aperture, cast analytically into the form of discrete time-convolution equations. The latter equations are subsequently solved via a stable marching-on-in-time scheme. Illustrative examples are presented and validated using a 3D numerical EM tool.

Pulsed electromagnetic (EM) field transmission through a relatively small rectangular aperture is analyzed with the aid of the Cagniard-deHoop method of moments (CdH-MoM). The classic EM scattering problem is formulated using the EM reciprocity theorem of the time-convolution type. The resulting TD reciprocity relation is then, under the assumption of piecewise-linear, space-time magnetic-current distribution over the aperture, cast analytically into the form of discrete time-convolution equations. The latter equations are subsequently solved via a stable marching-on-in-time scheme. Illustrative examples are presented and validated using a 3D numerical EM tool.

Conference on Terahertz Photonics II Part of SPIE Photonics Europe Conference -- APR 03-MAY 20, 2022 -- ELECTR NETWORK, The aim of this study is to investigate and design broadband, terahertz antennas for the time-domain, pulsed operation of the photoconductive sources and detectors. Different antenna types, i.e., thick dipole, bowtie, and spiral antenna, are designed, and their performances are analyzed both analytically and numerically for radiation in 0.8-2 THz band. A very effective ultra-wideband antenna configuration, Archimedean spiral antenna, which has promising time-domain radiation results according to analytical studies, is proposed for terahertz radiation. To the best of the authors' knowledge, this is the first study on fully time-domain analysis of terahertz antennas operating in 0.8-2 THz band., This project is supported by TUBITAK under grant 119E501., SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ Strasbourg, TUBITAK [119E501]

Conference on Integrated Photonics Platforms II -- APR 03-MAY 20, 2022 -- ELECTR NETWORK, The limited bandwidth of conventional phase-shifter-based antenna arrays, which is caused by steering in different angles at different frequencies named as the beam-squint effect, is a problem that should be taken into consideration for the ultrawide band systems. To overcome this problem, designing optical true time delay (TTD) lines for the antenna arrays is crucial for the development of next-generation, wideband communication, and imaging systems, which employ short pulses for wideband operation. One of the important problems for employing such short pulses is the dispersion during the propagation along the on-chip optical waveguides, which cause the distortion in the pulse shape and decrease in the amplitude of the pulse. Therefore, we propose a one-dimensional (1D) fishbone grating waveguide with a Lego type of step taper on silicon-on-insulator (SOI) substrate, both of which are designed for time-domain operation. The designed grating waveguide/taper pair is excited by a pulsed Gaussian light source, having a FWHM of 90 fs at a center wavelength of 1550 nm, where we investigate the possibility of controlling the dispersion by using SiO2 cladding modulation and taper structure optimization using genetic algorithm. The simulation results show that it is possible to decrease the dispersion in terms of the amplitude of the pulse up to 85%. The simulation results also show that the coupling efficiency from the taper to the waveguide can be increased up to 73%, which also decrease the dispersion of the pulse significantly. The simulated bandwidth of the grating waveguide/taper pair is found to be 56 nm, which allows ultrawide band operation., H.A.G. acknowledges the partial support from the Scientific and Technical Research Council (TUBITAK) 2210A Grant. This project is funded by TUBITAK 119E501., SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ Strasbourg, Scientific and Technical Research Council (TUBITAK) [2210A]; TUBITAK [119E501]

Conference on Terahertz Photonics II Part of SPIE Photonics Europe Conference -- APR 03-MAY 20, 2022 -- ELECTR NETWORK, The aim of this study is to investigate and design broadband, terahertz antennas for the time-domain, pulsed operation of the photoconductive sources and detectors. Different antenna types, i.e., thick dipole, bowtie, and spiral antenna, are designed, and their performances are analyzed both analytically and numerically for radiation in 0.8-2 THz band. A very effective ultra-wideband antenna configuration, Archimedean spiral antenna, which has promising time-domain radiation results according to analytical studies, is proposed for terahertz radiation. To the best of the authors' knowledge, this is the first study on fully time-domain analysis of terahertz antennas operating in 0.8-2 THz band., This project is supported by TUBITAK under grant 119E501., SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ Strasbourg, TUBITAK [119E501]

Conference on Integrated Photonics Platforms II -- APR 03-MAY 20, 2022 -- ELECTR NETWORK, The limited bandwidth of conventional phase-shifter-based antenna arrays, which is caused by steering in different angles at different frequencies named as the beam-squint effect, is a problem that should be taken into consideration for the ultrawide band systems. To overcome this problem, designing optical true time delay (TTD) lines for the antenna arrays is crucial for the development of next-generation, wideband communication, and imaging systems, which employ short pulses for wideband operation. One of the important problems for employing such short pulses is the dispersion during the propagation along the on-chip optical waveguides, which cause the distortion in the pulse shape and decrease in the amplitude of the pulse. Therefore, we propose a one-dimensional (1D) fishbone grating waveguide with a Lego type of step taper on silicon-on-insulator (SOI) substrate, both of which are designed for time-domain operation. The designed grating waveguide/taper pair is excited by a pulsed Gaussian light source, having a FWHM of 90 fs at a center wavelength of 1550 nm, where we investigate the possibility of controlling the dispersion by using SiO2 cladding modulation and taper structure optimization using genetic algorithm. The simulation results show that it is possible to decrease the dispersion in terms of the amplitude of the pulse up to 85%. The simulation results also show that the coupling efficiency from the taper to the waveguide can be increased up to 73%, which also decrease the dispersion of the pulse significantly. The simulated bandwidth of the grating waveguide/taper pair is found to be 56 nm, which allows ultrawide band operation., H.A.G. acknowledges the partial support from the Scientific and Technical Research Council (TUBITAK) 2210A Grant. This project is funded by TUBITAK 119E501., SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ Strasbourg, Scientific and Technical Research Council (TUBITAK) [2210A]; TUBITAK [119E501]

Nowadays the importance of image sensing for the optimization of industry processes, medicine, security, etc is unquestionable. This sensing is mostly implemented by an array of pixels that acquire information from the environment by capturing incident light. This acquired information could only consist on the color of each pixel, but it can be more complete in order to be more useful, for example including the time instant when the light beam was received. In this way, a depth reconstruction of the image can be made. The thesis below poses a solution to make this measurement and obtain the time of incidence of each pixel with a 180 nm CMOS technology. Using a local circuit at pixel level and a set of shared resources at different levels to optimize space and consumption. Using this technology, a resolution of 250 ps and a range of 15 bits has been achieved, being able to compact it into a pixel of 50 ?m on each side. This thesis details the procedures followed and the results obtained, including schematics, estimates of area and simulations of the complete system., Actualmente es innegable la importancia de la sensorización de imágenes para la optimización de procesos de industria, medicina, seguridad, etc. Esta sensorización es mayoritariamente implementada por una matriz de píxeles que adquieren información del entorno mediante la captación de la luz incidente. Esta información adquirida puede consistir únicamente en el color del punto en cuestión, pero puede llegar a ser más completa para ser más útil, por ejemplo incluyendo el instante temporal en el que se ha recibido el haz de luz. De esta manera se puede hacer una reconstrucción de la profundidad de los distintos puntos de la imagen. La tesis a continuacin propone una solucion para hacer esta medida y obtener el tiempo de recepción de cada pixel con una tecnología CMOS de 180 nm. Utilizando un circuito local a nivel píxel y un conjunto de recursos compartidos a diferentes niveles para optimizar espacio y consumo. Utilizando esta tecnología se ha obtenido una resolución de 250 ps y un rango de 15 bits logrando compactarlo en un pixel de 50 ?m de lado. Esta tesis detalla los procedimientos seguidos y los resultados obtenidos, incluyendo esquemáticos, estimaciones de layout y simulaciones del sistema completo., Actualment és innegable la importància de la sensorització d’imatges per a l’optimització de processos d’indústria, medicina, seguretat, etc. Aquesta sensorització és majoritàriament implementada per una matriu de píxels que adquireixen informació de l’entorn mitjançant la captació de la llum incident. Aquesta informació adquirida pot consistir únicament en el color del punt en qüestió, però pot arribar a ser més completa per tal de ser més útil, per exemple incloent l’instant temporal en què s’ha rebut el feix de llum. D’aquesta manera es pot fer una reconstrucció de la profunditat dels diferents punts de la imatge. La tesi a continuació proposa una solució per a fer aquesta mesura i obtenir el temps de recepció de cada píxel amb una tecnologia CMOS de 180 nm. Utilitzant un circuit local a nivell píxel i un conjunt de recursos compartits a diferents nivells per tal d’optimitzar espai i consum. Utilitzant aquesta tecnologia s’ha obtingut una resolució de 250 ps i un rang de 15 bits de mesures aconseguint compactar-ho en un píxel de 50 ‘m de costat. Aquesta tesi detalla els procediments seguits i els resultats obtinguts, incloent esquemàtics, estimacions de layout i simulacions del sistema complet.

The primary goal of this study is to infer a time-domain (TD) counterpart of the frequency domain leaky wave. To reach this goal, a number of challenging problems will be tackled: (1) Develop adequate computational tools for performing detailed TD electromagnetic (EM) analyses via CST Studio simulations, the post-processing of the results included. (2) The TD study of the radiation from a gap-fed long slot at an air-dielectric interface. (3) The TD study of the radiation from a gap-fed long slot located just below an air-dielectric interface. The results of these explorations represent a first step towards establishing a causal counterpart of the leaky-wave radiation., Electrical Engineering | Wireless Communication and Sensing

We demonstrate a digital twin for failure detection in optical networks. Artificial neural networks-based models for optical constellation analysis enable predicting the transmitted signal in the time domain whereas analytical models are usually used to estimate their spectral evolution., This project has received funding from the European Union Horizon 2020 MSCA-EID MENTOR (G.A. 956713), the H2020 B5G-OPEN (G.A. 101016663), the MICINN IBON (PID2020- 114135RB-I00), and the ICREA Institution., Peer Reviewed, Postprint (author's final draft)

The aim was to assess the association between fetal growth restriction (FGR) and fetal heart rate variability (FHRV) in relation to fetal movements. A prospective observational cohort study was performed. Non-invasive fetal electrocardiography (NI-FECG) allowed beat-to-beat assessments with <5% corrections of RR intervals. FHRV analyses included: Root mean square of successive RR interval differences (RMSSD), high frequency power (HF power), and low frequency power (LF power). Fetal movements were categorized by continuous ultrasound scanning. We enrolled 36 singleton pregnant women expecting a small fetus (< the 2.3 percentile of mean weight for gestational age) diagnosed by ultrasound, of whom 25 presented with a birthweight < the 2.3 percentile. Among these, 11 were excluded due to low quality NI-FECG recordings, leaving 14 women with 28 recordings eligible for inclusion in the analyses. The control group consisted of 22 healthy fetuses with birthweights between the 10th and the 90th percentile (average for gestational age [AGA]). In FGR fetuses the HRV response to respiratory activity was comparable to that of AGA fetuses. RMSSD (Ratio 1.54 [95% CI: 1.33; 1.79]) and HF power (Ratio 2.88 [95% CI: 2.12; 3.91]) increased, whereas LF/HF power (Ratio: 0.44 [95% CI: 0.31;0.63]) decreased. However, during fetal quiescence, FGR fetuses differed significantly from AGA fetuses. Compared to AGA fetuses, FGR fetuses displayed lower RMSSD (Ratio 0.77 (95% CI: 0.58; 1.02)) and HF power (Ratio 0.56 (95% CI:0.32; 0.98)). This reduction was associated with the severity of the FGR. In conclusion, FGR fetuses displayed a respiratory sinus arrhythmia (RSA) comparable to AGA fetuses; however, more important, parameters representing cardiac vagal activity were impaired in FGR fetuses during quiescence. RSA may constitute an intrinsic function of the cardiovascular system, which is unaffected by fetal compromise. However, the basic cardiac outflow assessed during fetal qui

Multi-sensor technology has been widely applied in the condition monitoring of rail transit. In practice, the data of some channels in the high channel counts are often abnormal or lost due to the abnormality and damage of the sensors, thus resulting in a large amount of data waste. A method for the data recovery of lost channels by using adjacent channel data is proposed to solve this problem. Based on the LSTM network algorithm, a data recovery model is established based on the “sequence-to-sequence” regression analysis of adjacent channel data. Taking the measured vibration data of a subway as an example, the network is trained with multi-channel measured data to recover the lost channel data of time-series characteristics. The results show that this multi-channel data recovery model is feasible, and the accuracy is up to 98%. This method can also further reduce the number of channels that need to be collected.

Deterministic predictions of wave induced ship motion are increasingly often used to enlarge the oper- ational envelope of ships that perform complex operations at open sea. The large amount of complex operations performed nowadays, motivates the relevance of motion predictions. The company Next Ocean provides these forecasts, based on linear seakeeping theory. While highly linear degrees of freedom are predicted accurately, roll motion predictions prove to be more demanding and are less accurate. This research aims to improve roll prediction accuracy by adding (non)linear damping to the equations of motion. The prediction optimization is performed on data of the platform supply vessel Acta Auriga. To enable the use of nonlinear forces, the equations of motions are first implemented in the time domain using Cummins’ equations. The linear coefficients in this equation are determined from the frequency dependent coefficients in Acta Auriga’s hydrodynamic database. To ensure the correctness and investigate the limitations of the implemented Cummins equation, the results from the time and frequency domain are extensively compared. Both monochromatic excitations, as well as spectrum (JONSWAP) excitations are considered. In contrast to linear force coefficients, nonlinear force coefficients are generally not known for a given vessel. Implementing these forces into the equations of motion imposes the need for an approximation of these coefficients. Estimates for the linear, quadratic and cubic viscous damping forces are made, using both the measured motions of a vessel operating at sea and the predictions of the corresponding excitation force, made by Next Ocean. A multivariate regression algorithm is used for the identification. The Cummins equation was successfully implemented. However, the translation from frequency to time domain was more error prone than anticipated; the frequency dependent coefficients need to meet requirements that are typically no, Marine Technology | Ship Hydromechanics

The present work applies several advanced spectral methods to the analysis of macroeconomic fluctuations in three countries of the European Union: Italy, The Netherlands, and the United Kingdom. We focus here in particular on singular-spectrum analysis (SSA), which provides valuable spatial and frequency information of multivariate data and that goes far beyond a pure analysis in the time domain. The spectral methods discussed here are well established in the geosciences and life sciences, but not yet widespread in quantitative economics. In particular, they enable one to identify and describe nonlinear trends and dominant cycles | including seasonal and interannual components that characterize the deterministic behavior of each time series. These tools have already proven their robustness in the application on short and noisy data, and we demonstrate their usefulness in the analysis of the macroeconomic indicators of these three countries. We explore several fundamental indicators of the countries' real aggregate economy in a univariate, as well as a multivariate setting. Starting with individual single-channel analysis, we are able to identify similar spectral components among the analyzed indicators. Next, we consider combinations of indicators and countries, in order to take different effects of comovements into account. Since business cycles are cross-national phenomena, which show common characteristics across countries, our aim is to uncover hidden global behavior across the European economies. Results are compared with previous findings on the U.S. indicators (Groth et al., 2012). Finally, the analysis is extended to include several indicators from the U.S. economy, in order to examine its influence on the European market.

KM3NeT is a multi-purpose cubic-kilometer neutrino observatory in construction in the Mediterranean Sea. It consists of ORCA and ARCA (for Oscillation and Astroparticle Research with Cosmics in the Abyss, respectively); currently both have a few detection lines in operation. Although having different primary goals, both detectors can be used to do neutrino astronomy over a wide energy range, from a few GeV to a few tens of PeV. In view of the growing field of time-domain astronomy, it is increasingly crucial to be able to identify neutrinos in real-time. This online neutrino sample will serve to trigger neutrino alerts that will be sent to the astronomy community and to look for time/space coincidence around external electromagnetic and multi-messenger triggers. These real-time searches can significantly increase the discovery potential of transient cosmic accelerators and refine the pointing directions in the case of poorly localized triggers, such as gravitational waves. In the field of core-collapse supernovae (CCSN), the detection of the MeVscale CCSN neutrinos is crucial as an early warning. KM3NeT’s digital optical modules act as good detectors for these neutrinos. This proceeding presents the status of KM3NeT’s real-time multi-messenger activities, including supernova monitoring, online event reconstruction, event classification and selection, alert distribution, and the first test of the selection on data., Article signat per 297 autors/es: M.Ageron, S. Aiello, A. Albert, M. Alshamsi, S. Alves Garre, Z. Aly, A. Ambrosone, F. Ameli, M. Andre, G. Androulakis, M. Anghinolfi, M. Anguita, G. Anton, M. Ardid, S. Ardid, W. Assal, J. Aublin, C. Bagatelas, B. Baret, S. Basegmez du Pree, M. Bendahman, F. Benfenati, E. Berbee, A. M. van den Berg, V. Bertin, S. Beurthey, V. van Beveren, S. Biagi, M. Billault, M. Bissinger, M. Boettcher, M. Bou Cabo, J. Boumaaza, M. Bouta, C. Boutonnet, G. Bouvet, M. Bouwhuis, C. Bozza, H.Brânzas, R. Bruijn, J. Brunner, R. Bruno, E. Buis, R. Buompane, J. Busto, B. Caiffi, L. Caillat, D. Calvo, S. Campion, A. Capone, H. Carduner, V. Carretero, P. Castaldi, S. Celli;, R. Cereseto, M. Chabab, C. Champion, N. Chau, A. Chen, S. Cherubini, V. Chiarella, T. Chiarusi, M. Circella, R. Cocimano, J. A. B. Coelho, A. Coleiro, M. Colomer Molla, S. Colonges, R. Coniglione, A. Cosquer, P. Coyle, M. Cresta, A. Creuso, A. Cruz, G. Cuttone, A. D’Amico, R. Dallier, B. De Martino, M. De Palma, I. Di Palma, A. F. Díaz, D. Diego- Tortosa, C. Distefano, A. Domi, C. Donzaud, D. Dornic, M. Dörr, D. Drouhin, T. Eberl, A. Eddyamoui, T. van Eeden, D. van Eijk, I. El Bojaddaini, H. Eljarrari, D. Elsaesser, A. Enzenhöfer, V. Espinosa, P. Fermani, G. Ferrara, M. D. Filipovic, F. Filippini, J. Fransen, L. A. Fusco, D. Gajanana, T. Gal, J. García Méndez, A. Garcia Soto, E. Garçon, F. Garufi, C. Gatius, N. Geißelbrecht, L. Gialanella, E. Giorgio, S. R. Gozzini, R. Gracia, K. Graf, G. Grella, D. Guderian, C. Guidi, B. Guillon, M. Gutiérrez, J. Haefner, S. Hallmann, H. Hamdaoui, H. van Haren, A. Heijboer, A. Hekalo, L. Hennig, S. Henry, J. J. Hernández-Rey, J. Hofestädt, F. Huang,W. Idrissi Ibnsalih, A. Ilioni, G. Illuminati, C.W. James, D. Janezashvili, P. Jansweijer, M. de Jong, P. de Jong, B. J. Jung, M. Kadler, P. Kalaczynski, O. Kalekin,U. F. Katz, F. Kayzel, P.Keller, N. R. Khan Chowdhury, G. Kistauri, F. van der Knaap, P. Kooijman, A. Kouchner, M. Kreter, V. Kulikovskiy, M. La, Postprint (published version)

This thesis presents the development, testing, and verification of transmission tomography software for the applications of small-scale biological imaging and large-scale stored-grain imaging. Transmission tomography is a non-invasive technique for producing quantitative images of an object's physical properties. This is done by interrogating the object with waves and measuring the resulting response at a set of measurement positions. The properties of the received waves are analyzed, and used to calculate the properties of the object which is interrogated. First, a mathematical formulation of transmission tomography is presented and explained. The formulation is then used to build a numerical model of the physical properties which dictate wave transmission in two systems of linear algebraic equations. The algorithms that are required for building the numerical model are then explained. The rest of this thesis is devoted to a series of experiments. These experiments show the usefulness of transmission tomography in some particular applications. They also motivate the incremental development of features of the transmission tomography algorithm that was developed for this thesis. The first experiment uses acoustic data to perform two-dimensional transmission tomography. The first experiment shows that two-dimensional transmission tomography of acoustic data produces useful images of an object's wave speed. The successful two-dimensional experiments motivate the two following experiments, which use electromagnetic data to perform three-dimensional transmission tomography. In order to perform three-dimensional tomography of electromagnetic data, a modification is made to the numerical model. The successful three-dimensional transmission tomography algorithm is then applied to track the volume of grain stored in a bin. The final experiment uses acoustic data and the modified numerical model to perform three-dimensional transmission tomography to identify two distinct sph

A study is established regarding the behavior of the vehicle under the influence of the damping elements, proposing a methodology for the validation of the technical state of the dampers through the registration of dynamic variables under commercial operating conditions of the vehicle, by applying the Operational Modal Analysis COMA) technique via Least-Square Complex Exponential (LSCE) method to experimental tests and numeric simulations to a multi-body system (MBS) model. The OMA-LSCE method is applied to the signals acquired during a test performed on a passenger of a three- car unit in typical commercial travel operation. From the signals in time domain of each section of the segment, the respective discrete function PSD is calculated. Once the model is defined, a set of numeric simulation is executed according to the design of the experiment. The results of the numeric simulations show that the natural frequency generates a lineal regressive model with correlation coefficient values.

A study is established regarding the behavior of the vehicle under the influence of the damping elements, proposing a methodology for the validation of the technical state of the dampers through the registration of dynamic variables under commercial operating conditions of the vehicle, by applying the Operational Modal Analysis COMA) technique via Least-Square Complex Exponential (LSCE) method to experimental tests and numeric simulations to a multi-body system (MBS) model. The OMA-LSCE method is applied to the signals acquired during a test performed on a passenger of a three- car unit in typical commercial travel operation. From the signals in time domain of each section of the segment, the respective discrete function PSD is calculated. Once the model is defined, a set of numeric simulation is executed according to the design of the experiment. The results of the numeric simulations show that the natural frequency generates a lineal regressive model with correlation coefficient values.

In the paper, the pursued objective is to take advantage of two main relevant cascade methods, namely Ensemble Empirical Mode Decomposition (EEMD) and Discrete Wavelet Transform (DWT), for the improvement of the sensitivity of scalar indicators such as Kurtosis (Kurt) and Crest Factor (CF) within the application of condition monitoring by vibration analysis on electric machines. The measurements were possible thanks to the piezoelectric sensors, where the signals were recorded from the machine's critical and judiciously chosen points. The paper demonstrates that when the motor runs under faulty conditions, it is possible to notice the appearance of spallings, which cause the signal to be disturbed and consequently modify the distribution (which is of Gaussian kind in a flawless situation). Nevertheless, those impulse excitations can have a tremendous effect on the values of time-domain indicators. The paper proposes two powerful denoising methods, discussed in-depth the effectiveness of each technique. The conclusion drawn from the analysis shows that the approach improves the sensitivity of selected indicators and therefore increases their reliability for fault presence detection. © 2021 IEEE., Export Date: 20 September 2021; Conference Paper; CODEN: CRIIE

[EN] The mechanical vibrations of fuel assemblies have been shown to give rise to high levels of neutron noise, triggering in some circumstances the necessity to operate nuclear reactors at a reduced power level. This work analyses the effect in the neutron field of the oscillation of one single fuel assembly. Results show two different effects in the neutron field caused by the fuel assembly vibration. First, a global slow variation of the total reactor power due to a change in the criticality of the system. Second, an oscillation in the neutron flux in-phase with the assembly vibration. This second effect has a strong spatial dependence that can be used to localize the oscillating assembly. This paper shows a comparison between a time-domain and a frequency-domain analysis of the phenomena to calculate the spatial response of the neutron noise. Numerical results show a really close agreement between these two approaches.

The paper presents a wave basin experiment of a direct-driven point-absorber wave energy converter moving in six degrees of freedom. The goal of the work is to study the dynamics and energy absorption of the wave energy converter, and to verify under which conditions numerical models restricted to heave can capture the behaviour of a point-absorber moving in six degrees of freedom. Several regular and irregular long-crested waves and different damping values of the power take-off system have been tested. We collected data in terms of power output, device motion in six degrees of freedom and wave elevation at different points of the wave basin. A single-body numerical model in the frequency domain and a two-body model in the time domain are used in the study. Motion instabilities due to parametric resonance observed during the experiments are discussed and analysis of the buoy motion in terms of the Mathieu instability is also presented. Our results show that the simplified models can reproduce the body dynamics of the studied converter as long as the transverse non-linear instabilities are not excited, which typically is the case in irregular waves. The performance of the more complex time domain model is able to reproduce both the buoy and PTO dynamics, while the simpler frequency domain model can only reproduce the PTO dynamics for specific cases. Finally, we show that the two-body dynamics of the studied wave energy converter affects the power absorption significantly, and that common assumptions in the numerical models, such as stiff mooring line or that the float moves only in heave, may lead to incorrect predictions for certain sea states.

The time domain-electric field integral equation (TD-EFIE) and its differentiated version are widely used to simulate the transient scattering of a time dependent electromagnetic field by a perfect electric conductor (PEC). The time discretization of the TD-EFIE can be achieved by a space-time Galerkin approach or, as it is considered in this contribution, by a convolution quadrature using implicit Runge-Kutta methods. The solution is then computed using the marching-on-in-time (MOT) algorithm. The differentiated TD-EFIE has two problems: 1) the system matrix suffers from ill-conditioning when the time step increases (low frequency breakdown) and 2) it suffers from the DC instability, i.e., the formulation allows for the existence of spurious solenoidal currents that grow slowly in the solution. In this article, we show that 1) and 2) can be alleviated by leveraging quasi-Helmholtz projectors to separate the Helmholtz components of the induced current and rescale them independently. The efficacy of the approach is demonstrated by numerical examples including benchmarks and real-life applications., Numerical Analysis

In the vicinity of locks and bridge piers, guide works are placed in order to steer inland navigation vessels through a narrowed passage. The design of these structures is generally done in a static way, thus without consideration of time-dependent phenomena. By treating the contact force during a brush collision as a static force, several phenomena are overlooked. First of all, it is possible that, in case of a brush collision, a second impact occurs due to the yawing motion of the vessel that is generated during the first impact. Considering the time domain in the analysis of brush collisions also enables the investigation of the length that is required for a guide work to fulfill its function. Within this thesis the time aspect is considered for brush collisions between inland navigation vessels and guide works with steel hollow tubular cross-sections.Objective of this research is to quantify the second impact and to provide a recommendation for the length of guide works, in order to answer the question: “In what ways is the design of guide works affected by taking into account the time domain?. A parametric tool that simulates brush collisions is created in Python. By variation of one parameter at a time, the influence of this parameter on the magnitude of the second impact and the required length for a guide work is visualised. Eventually, the model created in Python is translated to SCIA Engineer. By using the automatic post-processing environment of the Finite Element Software, this translation can be used to speed up the design guide works in future projects. On top of that, the influence of torsion on the mechanical behaviour of the structure is taken into account. For the investigated parameters a second impact always occurs within the 90 seconds of performed analysis, except for vessels with a large mass or length, or a small initial velocity. On top of that, the contact force during the second impact generally appears to be 30 to 40 percent larger t, Civil Engineering | Structural Engineering

In this article, we propose an alternative time-domain approach for the homogenization of multiturn windings with frequency-dependent parameters in finite-element (FE) models. First, an elementary 2-D FE characterization of the conductors is carried out over the frequency range of interest to obtain the frequency-dependent parameters and account for the eddy-current effects in the winding. These complex coefficients are subsequently associated with an equivalent Foster network and translated into the time domain via the inverse Laplace transform. The resulting time-domain equations are solved with a recursive convolution scheme. No extra degrees of freedom are required in the homogenized winding. The results of the homogenized model present an excellent agreement with those obtained by an accurate but expensive FE model in which all turns are explicitly discretized. The proposed approach is further compared with a previously developed time-domain homogenization technique based on RL Cauer networks., SCOPUS: ar.j, info:eu-repo/semantics/published

In this paper, an approach for the time-domain homogenization of foil windings in axisymmetric finite-element (FE) models is presented. The homogenized formulation is characterized by an axial current redistribution due to the skin effect and a radial inter-turn voltage given by the insulation in-between the turns. The method is successfully applied to an axisymmetric 20-turn foil-winding inductor. At low frequencies, the local and global results present an excellent agreement with those obtained by an accurate but expensive FE model in which all turns are explicitly discretized. The air-gap effect and the frequency limitations are studied as well., SCOPUS: ar.j, info:eu-repo/semantics/published

[EN] In a nuclear reactor, even operating at full power and steady-state conditions, fluctuations are detected in the recording of any process parameter. These fluctuations (also called noise) could be of various origins, such as, turbulence, mechanical vibrations, coolant boiling, etc. The monitoring and complete comprehension of those parameters should thus allow detecting, using existing instrumentation and without introducing any external perturbation to the system, possible anomalies before they have any inadvertent effect on plant safety and availability. In order to reproduce and study the induced neutron noise in a nuclear reactor core, it is compulsory to develop suitable tools. Existing time-domain codes were originally not developed for this type of calculations. Modifications of those codes and the development of an associated intricate methodology are necessary for enabling noise calculations. This involves, in some cases, changes in the source code and the development of new auxiliary tools to ensure accurate reproductions of the core behavior under the existence of a neutron noise source. In the proposed work, the time-domain neutron diffusion code PARCS is used to model the effect of stationary perturbations representative of given neutron noise sources. In order to validate the feasibility of the time-dependent methodology thus developed, comparisons with the results of simulations performed in the frequency domain, using the CORE SIM tool, developed at Chalmers University of Technology, are performed. The development of a few test cases based on a real reactor model are undertaken as the basis for such comparisons and a methodology aimed at assessing the time-domain simulations versus the frequency-domain simulations is established. It is demonstrated that PARCS, although not primarily developed for neutron noise calculations, can reproduce neutron noise patterns for reasonable frequencies. However, it is also observed that unphysical results are o

The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands of transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use of the large data set by taking advantage of the temporal nature of the data, and further combining it with other data sets. We start with the initial steps of separating bogus candidates from real ones, separating stars and galaxies, and go on to the classification of real objects into various classes. Besides the usual methods (e.g., based on features extracted from light curves) we also describe early plans for alternate methods including the use of domain adaptation, and deep learning. In a similar fashion we describe efforts to detect fast moving asteroids. We also describe the use of the Zooniverse platform for helping with classifications through the creation of training samples, and active learning. Finally we mention the synergistic aspects of ZTF and LSST from the ML perspective.

The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands of transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use of the large data set by taking advantage of the temporal nature of the data, and further combining it with other data sets. We start with the initial steps of separating bogus candidates from real ones, separating stars and galaxies, and go on to the classification of real objects into various classes. Besides the usual methods (e.g., based on features extracted from light curves) we also describe early plans for alternate methods including the use of domain adaptation, and deep learning. In a similar fashion we describe efforts to detect fast moving asteroids. We also describe the use of the Zooniverse platform for helping with classifications through the creation of training samples, and active learning. Finally we mention the synergistic aspects of ZTF and LSST from the ML perspective.

This master thesis report details the process of developing a simulation platform for radio transceivers with a focus on analog receiver front end system design. The platform was implemented in the National Instruments VSS environment for the company Ericsson AB.