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Humanity’s interest is to explore the unknown, discover new worlds, find traces of life and understand the creation of our solar system. Interplanetary orbital propagators are developed in that context. They consist of tools allowing us to predict the spacecraft trajectories in our solar system. Propagators are used to support and design real-world missions. The main objective of the thesis is to develop a high-fidelity orbital propagator for interplanetary space missions. It is implemented in the MATLAB environment. The propagator should include accurate ephemerides of our solar system and high-fidelity dynamical models. More specifically, perturbations due to the non-sphericity of the attractors, the solar radiation pressure, eclipse models and point mass gravity attractions should be taken into account. Lambert’s problem should also be included in the propagator. The general mission analysis tool GMAT R2017a developed by NASA is used to validate the results. The semi- analytic method VSOP87 based on integrated ephemeris DE200 is implemented in the propagator. The semi- analytic method VSOP87 takes into account the secular and periodic perturbations between the considered planet and the other celestial bodies (planets and asteroids). The errors represent respectively 0.003% and 0.01% of the semi-major axes of the inner planets and of the outer planets. The accuracy of the point mass gravity and solar radiation pressure models is directly linked to the accuracy of planetary ephemerides. The J2 perturbation is independent of the ephemerides. It is validated with the S3L propagator developed by the University of Liege. The dominant point mass gravity perturbations within the spheres of influence come from the moons. The close proximity between the moons and the spacecraft is the key parameter explaining this fact. Only Earth’s moon called Moon is modelled in the propagator. The Sun is the second contributor due its large gravitational parameter. Propagation lasting one day have been performed each day on January 2000 on an orbit escaping the Earth. The Moon changes the final spacecraft position by 75 km on average compared to the two-body trajectory, whereas the Sun changes it by 31 km on average compared to the two- body trajectory. These distances represent the errors with respect to GMAT the point mass gravity models included in the propagator should compensate. It is expected that these values approach 0. The averages of errors in final spacecraft positions for the Moon and Sun point mass gravity models reduce respectively to 1 km and 4 m. The approximate ephemerides of the Moon come from Astronomical Almanac which provides less accurate ephemerides than the VSOP87 planetary theory. As a result, the Moon point mass model gives rise to less accurate results. However, it reduces the error from 75 km to 1 km on average. In contrast, the Sun point mass gravity model reduces the error from 31 km to 4 m on average. The planetary point mass gravity perturbations are included to obtain high-fidelity propagation within the spheres of influence. In contrast, the planetary point mass perturbations change significantly the spacecraft trajectories outside the spheres of influence. A cannonball model and the eclipse model proposed in Curtis are chosen to model the solar radiation pressure perturbation. The eclipse model included in the propagator overestimates the shadow region compared to the conical eclipse model included in GMAT. However, for Mercury, which is the planet located the closest to the Sun, the error on the final position decreases from 11.23 m to 0.59 m by taking into the eclipse model. The distance, 11.23 m, is found considering that the spacecraft is in full illumination during the one day of propagation around Mercury. Eventually, the solar radiation pressure model is validated with long propagation. The case study is an interplanetary trajectory between the Earth and Mars in 309 days. After 300 days of propagation, the error compared to GMAT is 11 km which represents an error of 0.007 %. Lambert’s problem coupled with the perturbation models is used to recreate the four first years of the Cassini- Huygens mission. The data of the reference curve come from JPL Horizons Ephemeris System. The mean relative error between the curves of the Cassini-Huygens mission and the propagator is 1.95%.

propagator --- Solar radiation pressure --- Point mass gravity perturbations --- ephemerides --- Lambert's problem --- Cassini-Huygens mission --- sphere of influence --- J2 perturbation --- Ingénierie, informatique & technologie > Ingénierie aérospatiale

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Modelling and simulation in acoustics is currently gaining importance. In fact, with the development and improvement of innovative computational techniques and with the growing need for predictive models, an impressive boost has been observed in several research and application areas, such as noise control, indoor acoustics, and industrial applications. This led us to the proposal of a special issue about “Modelling, Simulation and Data Analysis in Acoustical Problems”, as we believe in the importance of these topics in modern acoustics’ studies. In total, 81 papers were submitted and 33 of them were published, with an acceptance rate of 37.5%. According to the number of papers submitted, it can be affirmed that this is a trending topic in the scientific and academic community and this special issue will try to provide a future reference for the research that will be developed in coming years.

Research & information: general --- noise barrier --- insertion loss --- vehicle frequencies --- diffraction --- flow speed --- Analytical solutions --- FDTD --- EMATs --- beam directivity --- perforate tube silencer --- transmission loss (TL) --- pressure loss --- computational fluid dynamics (CFD) --- temperature --- air flow velocity --- graphical bilinear method --- seismic survey --- dynamic cone penetration test --- soil depth --- time-distance curve --- KZK equation --- fractional order derivative --- ultrasound hyperthermia --- HIFU --- acoustic simulation --- Kramers–Kronig relation --- stereo audio coding --- Principal Component Analysis (PCA) --- multi-frame --- Pyramid Vector Quantization (PVQ) --- bowel sound --- bowel motility --- automatic detection/evaluation --- power-normalized cepstral coefficients --- noncontact instrumentation --- acoustic localization --- cross array --- moving sound source --- discrete sampling --- error analysis --- open-air theatres --- acoustical measurements --- prediction models --- historical acoustics --- Direction of Arrival (DOA) --- time-frequency (TF) mask --- speech sparsity --- speech enhancement (SE) --- acoustic vector sensor (AVS) --- intelligent service robot --- voice generation --- multichannel electroglottograph --- larynx acoustics --- fingerprinting acoustic localization --- iterative interpolation --- K-Means clustering --- Two-stage matching --- Adjacent RPs --- dynamic tissue property --- Westervelt equation --- thermal damage zone --- submerged floating tunnel (SFT) --- mooring line --- coupled dynamics --- hydro-elastic responses --- wet natural frequencies --- mooring tension --- seismic excitation --- wave excitation --- seaquake --- thick annular circular plate --- Rayleigh integral --- finite element modeling --- rectangular and concentric stiffener patches --- taper ratio --- thickness variation --- MRI --- Zone Plates --- ultrasonic lenses --- piano playing --- vibrotactile feedback --- interaction --- musical performance --- auditory perception --- sensors --- actuators --- crack growth --- acoustic echo --- COSMO --- p-value --- l1-regularized RLS --- sparsity --- room impulse response --- total least squares --- regularization factor --- fluid-filled polyethylene (PE) pipeline --- noise control --- acoustic propagation --- cutoff phenomenon --- UWA communication --- channel modelling --- OFDM --- channel estimation --- simulation platform --- minimum variance distortionless response --- signal self-cancellation --- direction estimation --- underwater acoustic source --- spatial power spectrum --- cochlear implant --- coding strategy --- Fixed-Channel --- Channel-Picking --- vocoder simulation --- normal-hearing --- point mass --- parabolic thickness variation --- landmine detection --- lumped parameter model --- prodder --- resonance frequency --- noised-induced hearing loss --- powered surgical instruments --- ultrasonic aspirator --- transcanal endoscopic ear surgery --- balanced armature receiver --- lumped parameter method --- finite element method and Boundary element method --- focused transducer --- acoustic field --- nonuniform radiation distribution --- Bessel radiation distribution --- spherically curved uniform radiator --- rim radiation --- Lamb waves --- wooden constructions --- acoustics --- low frequency noise --- modelling --- ultrasonic guided waves --- SAFE --- rail defect detection --- mode excitation --- solid dielectrics --- acoustic emission --- artificial neural networks --- electrical treeing --- wavelets --- non-destructive testing --- high-voltage insulating systems --- boundary element method --- Helmholtz equation --- structural health monitoring --- mooring chain --- fatigue crack growth --- structural integrity --- n/a --- Kramers-Kronig relation

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Modelling and simulation in acoustics is currently gaining importance. In fact, with the development and improvement of innovative computational techniques and with the growing need for predictive models, an impressive boost has been observed in several research and application areas, such as noise control, indoor acoustics, and industrial applications. This led us to the proposal of a special issue about “Modelling, Simulation and Data Analysis in Acoustical Problems”, as we believe in the importance of these topics in modern acoustics’ studies. In total, 81 papers were submitted and 33 of them were published, with an acceptance rate of 37.5%. According to the number of papers submitted, it can be affirmed that this is a trending topic in the scientific and academic community and this special issue will try to provide a future reference for the research that will be developed in coming years.

noise barrier --- insertion loss --- vehicle frequencies --- diffraction --- flow speed --- Analytical solutions --- FDTD --- EMATs --- beam directivity --- perforate tube silencer --- transmission loss (TL) --- pressure loss --- computational fluid dynamics (CFD) --- temperature --- air flow velocity --- graphical bilinear method --- seismic survey --- dynamic cone penetration test --- soil depth --- time-distance curve --- KZK equation --- fractional order derivative --- ultrasound hyperthermia --- HIFU --- acoustic simulation --- Kramers–Kronig relation --- stereo audio coding --- Principal Component Analysis (PCA) --- multi-frame --- Pyramid Vector Quantization (PVQ) --- bowel sound --- bowel motility --- automatic detection/evaluation --- power-normalized cepstral coefficients --- noncontact instrumentation --- acoustic localization --- cross array --- moving sound source --- discrete sampling --- error analysis --- open-air theatres --- acoustical measurements --- prediction models --- historical acoustics --- Direction of Arrival (DOA) --- time-frequency (TF) mask --- speech sparsity --- speech enhancement (SE) --- acoustic vector sensor (AVS) --- intelligent service robot --- voice generation --- multichannel electroglottograph --- larynx acoustics --- fingerprinting acoustic localization --- iterative interpolation --- K-Means clustering --- Two-stage matching --- Adjacent RPs --- dynamic tissue property --- Westervelt equation --- thermal damage zone --- submerged floating tunnel (SFT) --- mooring line --- coupled dynamics --- hydro-elastic responses --- wet natural frequencies --- mooring tension --- seismic excitation --- wave excitation --- seaquake --- thick annular circular plate --- Rayleigh integral --- finite element modeling --- rectangular and concentric stiffener patches --- taper ratio --- thickness variation --- MRI --- Zone Plates --- ultrasonic lenses --- piano playing --- vibrotactile feedback --- interaction --- musical performance --- auditory perception --- sensors --- actuators --- crack growth --- acoustic echo --- COSMO --- p-value --- l1-regularized RLS --- sparsity --- room impulse response --- total least squares --- regularization factor --- fluid-filled polyethylene (PE) pipeline --- noise control --- acoustic propagation --- cutoff phenomenon --- UWA communication --- channel modelling --- OFDM --- channel estimation --- simulation platform --- minimum variance distortionless response --- signal self-cancellation --- direction estimation --- underwater acoustic source --- spatial power spectrum --- cochlear implant --- coding strategy --- Fixed-Channel --- Channel-Picking --- vocoder simulation --- normal-hearing --- point mass --- parabolic thickness variation --- landmine detection --- lumped parameter model --- prodder --- resonance frequency --- noised-induced hearing loss --- powered surgical instruments --- ultrasonic aspirator --- transcanal endoscopic ear surgery --- balanced armature receiver --- lumped parameter method --- finite element method and Boundary element method --- focused transducer --- acoustic field --- nonuniform radiation distribution --- Bessel radiation distribution --- spherically curved uniform radiator --- rim radiation --- Lamb waves --- wooden constructions --- acoustics --- low frequency noise --- modelling --- ultrasonic guided waves --- SAFE --- rail defect detection --- mode excitation --- solid dielectrics --- acoustic emission --- artificial neural networks --- electrical treeing --- wavelets --- non-destructive testing --- high-voltage insulating systems --- boundary element method --- Helmholtz equation --- structural health monitoring --- mooring chain --- fatigue crack growth --- structural integrity --- n/a --- Kramers-Kronig relation