Bibliographies thématiques / Newtonian noise

Littérature scientifique sur le sujet « Newtonian noise »

Auteur : Grafiati
Publié le 11 mars 2023

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Articles de revues sur le sujet "Newtonian noise"

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Trozzo, Lucia, et Francesca Badaracco. « Seismic and Newtonian Noise in the GW Detectors ». Galaxies 10, no 1 (22 janvier 2022) : 20. http://dx.doi.org/10.3390/galaxies10010020.

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Gravitational wave detectors aim to measure relative length variations of the order of ΔL/L≃10−21, or less. Thus, any mechanism that is able to reproduce such a tiny variation can, in principle, threaten the sensitivity of these instruments, representing a source of noise. There are many examples of such noise, and seismic and Newtonian noise are among these and will be the subject of this review. Seismic noise is generated by the incessant ground vibration that characterizes Earth. Newtonian noise is instead produced by the tiny fluctuations of the Earth’s gravitational field. These fluctuations are generated by variations of air and soil density near the detector test masses. Soil density variations are produced by the same seismic waves comprising seismic noise. Thus, it makes sense to address these two sources of noise in the same review. An overview of seismic and Newtonian noise is presented, together with a review of the strategies adopted to mitigate them.
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Badaracco, Francesca. « Environmental noises in current and future gravitational-wave detectors ». Journal of Physics : Conference Series 2156, no 1 (1 décembre 2021) : 012077. http://dx.doi.org/10.1088/1742-6596/2156/1/012077.

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Abstract Gravitational–wave (GW) detectors are very sensitive instruments that suffer from a huge number of noises. If we aim to observe gravitational waves with earthbound detectors, we need to take care of every source that can prevent the observation. Seismic noise poses a huge challenge to the sensitivity in the the low-frequency band and it is tackled with suspensions and active controls. The low–frequency band can also be threatened by the so–called Newtonian noise, generated by the fluctuations of the gravity field. If this has not been a problem in the first generation gravitational-wave detectors, it will be so in the next runs and especially in the third–generation detectors, like the Einstein Telescope. We need then to be prepared to suppress as much as possible these noises, otherwise they might become the last wall for the sensitivity of our detectors. This manuscript will explore environmental noises with a particular detail on Newtonian and seismic noise and the techniques that we can employ to reduce their effects.
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Tauviqirrahman, Mohammad, J. Jamari, S. Susilowati, Caecilia Pujiastuti, Budi Setiyana, Ahmad Hafil Pasaribu et Muhammad Imam Ammarullah. « Performance Comparison of Newtonian and Non-Newtonian Fluid on a Heterogeneous Slip/No-Slip Journal Bearing System Based on CFD-FSI Method ». Fluids 7, no 7 (2 juillet 2022) : 225. http://dx.doi.org/10.3390/fluids7070225.

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It is a well-known fact that incorporating a slip boundary into the contact surfaces improves bearing performance significantly. Regrettably, no research into the effect of slip on the behavior of journal bearing systems operating with non-Newtonian lubricants has been conducted thus far. The main purpose of this work is to explore the performance comparison of Newtonian and non-Newtonian fluid on a heterogeneous slip/no-slip journal bearing system. The tribological and acoustic behavior of journal bearing is investigated in this study using a rigorous program that combines CFD (computational fluid dynamics) and two-way FSI (fluid–structure interaction) procedures to simulate Newtonian vs. non-Newtonian conditions with and without slip boundary. The numerical results indicate that irrespective of the lubricant type (i.e., Newtonian or non-Newtonian), an engineered heterogeneous slip/no-slip pattern leads to the improvement of the bearing performance (i.e., increased load-carrying capacity, reduced coefficient of friction, and decreased noise) compared to conventional journal bearing. Furthermore, the influence of the eccentricity ratio is discussed, which confirms that the slip beneficial effect becomes stronger as the eccentricity ratio decreases. It has also been noticed that the Newtonian lubricant is preferable for improving tribological performance, whereas non-Newtonian fluid is recommended for lowering bearing noise.
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Paik, Ho Jung, et Jan Harms. « Newtonian noise cancellation in tensor gravitational wave detector ». Journal of Physics : Conference Series 716 (mai 2016) : 012025. http://dx.doi.org/10.1088/1742-6596/716/1/012025.

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Fenyvesi, Edit, József Molnár et Sándor Czellár. « Investigation of Infrasound Background Noise at Mátra Gravitational and Geophysical Laboratory (MGGL) ». Universe 6, no 1 (3 janvier 2020) : 10. http://dx.doi.org/10.3390/universe6010010.

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Infrasound and seismic waves are supposed to be the main contributors to the gravity-gradient noise (Newtonian noise) of the third-generation subterranean gravitational wave detectors. This noise will limit the sensitivity of the instrument at frequencies below 20 Hz. Investigation of its origin and the possible methods of mitigation have top priority during the designing period of the detectors. Therefore, long-term site characterizing measurements are needed at several subterranean sites. However, at some sites, mining activities can occur. These activities can cause sudden changes (transients) in the measured signal, and increase the continuous background noise, too. We have developed an algorithm based on discrete Haar transform to find these transients in the infrasound signal. We found that eliminating the transients decreases the variation of the noise spectra, and therefore results a more accurate characterization of the continuous background noise. We carried out experiments for controlling the continuous noise. Machines operating at the mine were turned on and off systematically in order to see their effect on the noise spectra. These experiments showed that the main contributor of the continuous noise is the ventilation system of the mine. We also estimated the contribution of infrasound Newtonian noise at MGGL to the strain noise of a subterranean GW detector similar to Einstein Telescope.
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Yue, Pengcheng, Hua Qu, Jihong Zhao et Meng Wang. « Newtonian-Type Adaptive Filtering Based on the Maximum Correntropy Criterion ». Entropy 22, no 9 (22 août 2020) : 922. http://dx.doi.org/10.3390/e22090922.

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This paper provides a novel Newtonian-type optimization method for robust adaptive filtering inspired by information theory learning. With the traditional minimum mean square error (MMSE) criterion replaced by criteria like the maximum correntropy criterion (MCC) or generalized maximum correntropy criterion (GMCC), adaptive filters assign less emphasis on the outlier data, thus become more robust against impulsive noises. The optimization methods adopted in current MCC-based LMS-type and RLS-type adaptive filters are gradient descent method and fixed point iteration, respectively. However, in this paper, a Newtonian-type method is introduced as a novel method for enhancing the existing body of knowledge of MCC-based adaptive filtering and providing a fast convergence rate. Theoretical analysis of the steady-state performance of the algorithm is carried out and verified by simulations. The experimental results show that, compared to the conventional MCC adaptive filter, the MCC-based Newtonian-type method converges faster and still maintains a good steady-state performance under impulsive noise. The practicability of the algorithm is also verified in the experiment of acoustic echo cancellation.
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Beker, M. G., J. F. J. van den Brand, E. Hennes et D. S. Rabeling. « Newtonian noise and ambient ground motion for gravitational wave detectors ». Journal of Physics : Conference Series 363 (1 juin 2012) : 012004. http://dx.doi.org/10.1088/1742-6596/363/1/012004.

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FRAEDRICH, KLAUS. « FICKIAN DIFFUSION AND NEWTONIAN COOLING : A CONCEPT FOR NOISE INDUCED CLIMATE VARIABILITY WITH LONG-TERM MEMORY ? » Stochastics and Dynamics 02, no 03 (septembre 2002) : 403–12. http://dx.doi.org/10.1142/s0219493702000492.

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Observed near surface air and soil temperature time series reveal a long-term memory, which is associated with a power-law scaling of the frequency spectra, S(ω) ~ ω- β with β ~ 0.6, lying between white and flicker noise, 0 < β < 1. As this power law scaling is not consistent with the Brownian motion concept of climate variability, Fickian diffusion is added to a Newtonian cooling relaxation to provide a more suitable analog of climatic fluctuations: (i) Diffusive plus random heat fluxes parametrise the turbulent mixing by synoptic scale eddy life cycles, affect tropospheric and near surface temperatures and excite a long-term memory regime with a β ~ 0.5 scaling. (ii) Newtonian cooling describes the near surface temperatures relaxing towards a global mean deep soil temperature and stabilises the system to a white noise response at very low frequencies. The long-term memory regime emerges from the high frequency scaling (β ~ 1.5), once temperatures become correlated in space due to diffusion, so that spatially averaged fluctuations correlate for times beyond the diffusion time scale. The long-term memory regime disappears into a white noise plateau (β ~ 0), when low frequencies exceed the damping time scale of Newtonian cooling. This system may be interpreted as a diffusive system relaxing towards the deep soil restoration temperature with an almost infinitely large time scale.
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Paik, Ho Jung, M. Vol Moody et Ronald S. Norton. « SOGRO — Terrestrial full-tensor detector for mid-frequency gravitational waves ». International Journal of Modern Physics D 29, no 04 (21 janvier 2019) : 1940001. http://dx.doi.org/10.1142/s0218271819400017.

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Laser interferometer gravitational-wave (GW) detectors are observing signals from merging black hole and neutron star binaries with a frequency window from 10[Formula: see text]Hz to several kHz. Future space-based laser interferometers will open a new window of 0.1[Formula: see text]mHz to 0.1[Formula: see text]Hz. In this paper, we discuss the possibility of constructing a terrestrial GW detector named Superconducting Omni-directional Gravitational Radiation Observatory (SOGRO), which can fill the missing frequency window, 0.1 to 10[Formula: see text]Hz, with astronomically interesting sensitivity. SOGRO measures all five tensor components of the spacetime metric, which results in uniform sensitivity for all-sky directions and enables identification of the source direction and wave polarization with a single detector. Seismic and Newtonian gravity noise pose the greatest challenges for constructing ground-based detectors below 10[Formula: see text]Hz. SOGRO utilizes enhanced mechanical and electrical stabilities of materials at cryogenic temperatures to reject common-mode seismic noise to a very high degree. Further, its full-tensor characteristic gives an advantage in the rejection of the Newtonian noise over conventional detectors.
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Carrillo, José A., Young-Pil Choi et Samir Salem. « Propagation of chaos for the Vlasov–Poisson–Fokker–Planck equation with a polynomial cut-off ». Communications in Contemporary Mathematics 21, no 04 (31 mai 2019) : 1850039. http://dx.doi.org/10.1142/s0219199718500396.

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We consider a [Formula: see text]-particle system interacting through the Newtonian potential with a polynomial cut-off in the presence of noise in velocity. We rigorously prove the propagation of chaos for this interacting stochastic particle system. Taking the cut-off like [Formula: see text] with [Formula: see text] in the force, we provide a quantitative error estimate between the empirical measure associated to that [Formula: see text]-particle system and the solutions of the [Formula: see text]-dimensional Vlasov–Poisson–Fokker–Planck (VPFP) system. We also study the propagation of chaos for the Vlasov–Fokker–Planck equation with less singular interaction forces than the Newtonian one.
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Thèses sur le sujet "Newtonian noise"

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Hunter-Jones, Nicholas R. « Novel approaches to Newtonian noise suppression in interferometric gravitational wave detection ». Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65529.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 63-65).
The Laser Interferometer Gravitational-wave Observatory (LIGO) attempts to detect ripples in the curvature of spacetime using two large scale interferometers. These detectors are several kilometer long Michelson interferometers with Fabry-Perot cavities between two silica test masses in each arm. Given Earth's proximity to various astrophysical phenomena LIGO must be sensitive to relative displacements of 1018 m and thus requires multiple levels of noise reduction to ensure the isolation of the interferometer components from numerous sources of noise. A substantial contributor to the Advanced LIGO noise in the 1-10 Hz range is Newtonian (or gravity gradient) noise which arises from local fluctuations in the Earth's gravitational field. Density fluctuations from seismic activity as well as acoustic and turbulent phenomenon in the Earth's atmosphere both contribute to slight variations in the local value of g. Given the direct coupling of gravitational fields to mass the LIGO test masses cannot be shielded from this noise. In an attempt to characterize and reduce Newtonian noise in interferometric gravitational wave detectors we investigate seismic and atmospheric contributions to the noise and consider the effect of submerging a gravitational wave detector.
by Nicholas R. Hunter-Jones.
S.B.
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BADARACCO, FRANCESCA. « Newtonian Noise studies in 2nd and 3rd generation gravitational-wave interferometric detectors ». Doctoral thesis, Gran Sasso Science Institute, 2021. http://hdl.handle.net/20.500.12571/16065.

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This thesis work fits in the Newtonian noise (NN) cancellation framework for gravitational-wave (GW) detectors of 2nd and 3rd generation. At frequencies below 20 Hz the NN affects GW detectors by generating gravity gradients that mask the GW signals that we want to measure. My work can be divided in three main tasks: the optimization of a seismic array for the NN cancellation in underground detectors, the optimization of a seismic array for Advanced Virgo + (which, respect to the former one, relied on seismic measurements and not on a seismic model) and the evaluation of the NN and the seismic field at the KAGRA site. I will briefly summarize in the following the main results of these three works. In the first work I performed a global optimization for finding the optimal locations of an array of sensors for the NN cancellation for underground detectors. Since we need to search for the optimal positions of N sensors in a 3D space, the computational efforts required are very demanding. At the present time, seismic correlations in the relevant frequency band for ET from 3Hz to 20Hz are not available. So we modelled the seismic field as isotropic and homogeneous. With this work I was able to assess the feasibility of applying active NN reduction in underground detectors and reaching a factor 10 of noise reduction with 15 sensors at 10 Hz. In 2019 this work was published. The second work I made during my PhD was conceptually similar to the previous one but very different in the approach used to solve it. Exploiting a theoretical model in Virgo was not an option given its complicated structure. I then used Virgo's seismic data to run the optimization of sensor locations. The main challenge here was that I had to perform a gaussian process regression over a 4D space, and not enough data were available for this purpose. I found a way to bypass the regression over the 4D space by exploiting the convolution theorem. This allowed me to perform the regression over a space with reduced dimension, i.e., in 2D. The global optimization algorithm was then run hundreds of times in order to statistically prove the global minimum, exactly as done in the work for the underground optimization. The results proved that with 15 seismometers we can reach a noise reduction factor of 3-7, which is enough for the aimed sensitivity of the next observing runs. The results of this work were then used to set the array that will be used to cancel the NN in Advanced Virgo +. This work has been published in 2020. This approach could also be useful in future, where it will be needed to optimize underground seismic arrays with real seismic data. Finally, in the third work I used seismic data collected in the Kamioka mine (where the gravitational-wave detector KAGRA is hosted) to investigate the seismic noise caused by the infrastructure and to calculate a NN budget. These are important aspects that need to be investigated in view of the 3rd generation GW detector Einstein Telescope. The data indicated that the infrastructure noise starts to be important well above 10 Hz, where the NN loses its impact on the detector and where the seismic isolation system is capable of killing the noise. Moreover, I used the data from three seismometers to perform a beamforming analysis and find the seismic velocities and the seismic wave main directions. The extracted values were then used as a reference for the estimation of the NN budget. For completeness, I also estimated the NN budget coming from surface Rayleigh waves. This was made by exploiting the data of the F-net network, in Japan. I then showed that the NN from surface and body waves can be neglected for KAGRA.
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CIRONE, ALESSIO. « Magnetic and Newtonian noises in Advanced Virgo : evaluation and mitigation strategies ». Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1001554.

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In the present study, I table the first detailed estimation of the magnetic noise contribution to the Advanced Virgo sensitivity to gravitational waves. I tackle the topic by performing experimental assessments and numerical finite element simulations, all accompanied by careful data analysis. Results suggest that the magnetic noise impact for Advanced Virgo is not dramatic, but it will eventually be a considerable issue once the detector will approach its final design. In anticipation of that, I propose a mitigation strategy based on passive magnetic field shielding. In the second part, I deal with seismic newtonian noise, focusing on two crucial aspects involving the noise cancellation pipeline. These are the choice of the subtraction filter and the optimization of the seismic sensor array placement. The former issue required the definition of a machine learning algorithm based on deep neural networks, and its fine tuning. Results give some indication of good performances compared to the standard Wiener filter approach. The problem of the sensors deployment is instead addressed with the finite element analysis of the actual Virgo infrastructure and underground soil layers surrounding the test masses.
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Le, Tiec Alexandre. « Coalescence de trous noirs en relativité générale & ; Le problème de la matière noire en astrophysique ». Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00521645.

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La première partie de cette thèse s'inscrit dans le cadre de la modélisation des ondes gravitationnelles en provenance des systèmes binaires coalescents de trous noirs, dans la perspective de leur détection par les antennes gravitationnelles terrestres LIGO/VIRGO et spatiale LISA. Nous étudions la dynamique relativiste de tels systèmes binaires d'objets compacts à l'aide de deux méthodes d'approximation en relativité générale : les développements post-newtoniens, et le formalisme de la force propre, une extension naturelle de la théorie des perturbations d'un trou noir ; nous démontrons la cohérence des résultats ainsi obtenus dans leur domaine de validité commun. Dans un second temps, nous combinons ces deux méthodes perturbatives afin d'estimer l'effet de recul gravitationnel lors de la coalescence de deux trous noirs de Schwarzschild ; nos résultats sont en très bon accord avec ceux obtenus par des simulations en relativité numérique. La seconde partie de cette thèse traite du problème de la matière noire en astrophysique. L'hypothèse de la matière noire rend compte de nombreuses observations indépendantes de l'échelle des amas de galaxies jusqu'aux échelles cosmologiques. Les observations à l'échelle galactique sont toutefois en bien meilleur accord avec la phénoménologie de la dynamique newtonienne modifiée (MOND), qui postule une modification des lois de la gravité en l'absence de matière noire. Nous proposons une troisième alternative : conserver la théorie de la gravitation standard, mais doter la matière noire d'une propriété de polarisabilité dans un champ gravitationnel, de façon à rendre compte de la phénoménologie de MOND à l'échelle des galaxies.
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Chapitres de livres sur le sujet "Newtonian noise"

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Cella, G. « Off-Line Subtraction of Seismic Newtonian Noise ». Dans Recent Developments in General Relativity, 495–503. Milano : Springer Milan, 2000. http://dx.doi.org/10.1007/978-88-470-2113-6_44.

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Mishra, Vijay Kumar, Sumanta Chaudhuri, Jitendra K. Patel et Arnab Sengupta. « Estimation of Parameter in Non-Newtonian Third-Grade Fluid Problem by Artificial Neural Network Under Noisy Data ». Dans Lecture Notes in Mechanical Engineering, 235–44. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7831-1_22.

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Mishra, Vijay Kumar, Auritro Samanta, Sumanta Chaudhuri et Daya Shankar. « Generation of Temperature Profile by Artificial Neural Network in Flow of Non-Newtonian Third Grade Fluid Through Two Parallel Plates Under Noisy Data ». Dans Lecture Notes in Mechanical Engineering, 173–85. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0159-0_16.

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KLASON, C., J. KUBÁT et O. QUADRAT. « FLOW PROPERTIES AND ELECTRICAL NOISE GENERATED DURING CAPILLARY FLOW OF NEWTONIAN LIQUIDS ». Dans Theoretical and Applied Rheology, 481–83. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-444-89007-8.50205-7.

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Actes de conférences sur le sujet "Newtonian noise"

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Jose, Roselyn, et Rachel Kalpana Kalaimani. « Optimization of Sensor Placement for Broadband Newtonian Noise Cancellation in GW Detectors ». Dans 2021 25th International Conference on System Theory, Control and Computing (ICSTCC). IEEE, 2021. http://dx.doi.org/10.1109/icstcc52150.2021.9607303.

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Jose, Roselyn, et Rachel Kalpana Kalaimani. « Reinforcement Learning based Multi-objective Optimization for Broadband Newtonian Noise Cancellation in GW Detectors ». Dans 2022 30th Mediterranean Conference on Control and Automation (MED). IEEE, 2022. http://dx.doi.org/10.1109/med54222.2022.9837284.

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Olunloyo, Vincent O. S., Charles A. Osheku et Sidikat I. Kuye. « Vibration and Stability Behaviour of Sandwiched Viscoelastic Pipes Conveying a Non-Newtonian Fluid ». Dans ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20065.

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Internal fluid flow parameters in conjunction with elastomechanical properties of conveyance systems have significantly modulated flow induced vibrations in pipeline and riser systems. Recent advances on the mechanics of sandwich elastic systems as effective vibration and noise reduction mechanisms have simulated the possibility of replacing traditional steel pipes with sandwich pipes in deepwater environment. The dynamic behaviour and stability of sandwich elastic pipes conveying a non-Newtonian fluid are investigated in this paper. For this problem, a set of generalised non-linear equations governing the vibration of sandwich pipes held together in pressurised environment and conveying a non-Newtonian fluid is presented. By linearizing the governing partial differential equation matching the problem physics, under slight perturbation of the internal fluid velocity and other flow variables closed form analytical results for the system dual natural frequencies and stability under external excitation are computed for field designs and applications. Results show that for a given length of pipe, beyond the critical velocity, instability increases with the velocity of conveyance.
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MILYUKOV, VADIM. « THE NEWTONIAN GRAVITATIONAL CONSTANT : THE HISTORY OF THE DETERMINATION AND THE ENVIRONMENTAL NOISE PROBLEM FOR THE EXPERIMENTAL MEASUREMENT ». Dans Proceedings of the Ninth Asia-Pacific International Conference. WORLD SCIENTIFIC, 2010. http://dx.doi.org/10.1142/9789814307673_0001.

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Uma, B., P. S. Ayyaswamy, R. Radhakrishnan et D. M. Eckmann. « Modeling of a Nanoparticle Motion in a Newtonian Fluid : A Comparison Between Fluctuating Hydrodynamics and Generalized Langevin Procedures ». Dans ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75019.

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A direct numerical simulation adopting an arbitrary Lagrangian-Eulerian based finite element method is employed to simulate the motion of a nanocarrier in a quiescent fluid contained in a cylindrical tube. The nanocarrier is treated as a solid sphere. Thermal fluctuations are implemented using two different approaches: (1) fluctuating hydrodynamics; (2) generalized Langevin dynamics (Mittag-Leffler noise). At thermal equilibrium, the numerical predictions for temperature of the nanoparticle, velocity distribution of the particle, decay of the velocity autocorrelation function, diffusivity of the particle and particle-wall interactions are evaluated and compared with analytical results, where available. For a neutrally buoyant nanoparticle of 200 nm radius, the comparisons between the results obtained from the fluctuating hydrodynamics and the generalized Langevin dynamics approaches are provided. Results for particle diffusivity predicted by the fluctuating hydrodynamics approach compare very well with analytical predictions. Ease of computation of the thermostat is obtained with the Langevin approach although the dynamics gets altered.
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Davidson, Drew A., et Gary L. Lehmann. « Squeeze Flow Study of a Colloidal Paste ». Dans ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems collocated with the ASME 2005 Heat Transfer Summer Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ipack2005-73394.

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Crucial to the development and characterization of thermal interface materials (TIMs) is an understanding of the squeeze flow process that is commonly used to form thin bond layers in micro-electronic assemblies. A single model TIM, a dense, fairly monomodal suspension of submicron alumina particles suspended in a silicone-based resin, is first characterized as a Bingham fluid using a parallel disk rotational viscometer. Next, the model TIM is squeezed from ∼1 mm initial thickness to ∼.01 mm limiting thickness under nominally constant applied load (68 to 345 kPa) between 20 mm diameter aluminum plates in an axial compression test apparatus (the type commonly used for materials testing). The test plates are flat (∼10 μm flatness deviation over the plate) and smooth (Ra ∼ 20 nm), and are fixed in the test column with epoxy for optimum parallelism. Bond layer thickness is estimated using the LVDT built into the compression tester. The thickness measurement resolution is limited by LVDT noise of 10–20 microns. Squeezing forces are well above the ∼.02 N noise level of the 100 N load cell. Of the test system compliance, inertia, and friction, only the compliance is significant to our testing, and is corrected for. Squeeze flow tests of Newtonian standards are used to qualify the test process. In the case of the model paste, Bingham fluid model parameters from rotational viscometry are used in a lubrication model of squeeze flow that shows good agreement with the measured gap vs. time behavior during squeezing. Improved agreement is obtained by including plate flatness deviation and time-dependent force in the lubrication model. Parallel disk viscometry and squeeze flow testing of the base resin of the model TIM shows Newtonian behavior.
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Naz, Saima, Doug Lockhart, Peter Harwood et Alexandra E. Komrakova. « Numerical Study of Turbulent Rotating Flow in a Tesla Disc Pump ». Dans ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71577.

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The advantages of Tesla’s bladeless turbine over the conventional bladed turbine — such as an easier manufacturing process; low cost; low noise; the ability to operate with different working fluids, including Newtonian and non-Newtonian fluids; and single phase or multi-phase systems [1] — keep the design development of this device a subject of ongoing research. The first design of the Tesla turbine was presented by N. Tesla in 1913 [2]. In the 60s and 70s, a number of research groups built the Tesla device to investigate its performance (power, torque, efficiency) [3]–[6]. At the present time, the efficient design of the Tesla device is still a focus of experimental and numerical research studies [7]–[13]. In this work, the computational fluid dynamics (CFD) simulations are performed to study three-dimensional turbulent compressible flow between the two corotating discs. The wide gap between the discs results in a Reynolds number of 1656, which is calculated based on the disc gap and the rotational speed of the discs. The CO2 gas is used as a working fluid. The simulations are performed using the commercial CFD software (STAR-CCM+, SIEMENS PLM). In this study, we determined the inlet and outlet boundary conditions together with the rotational speed of the discs that make the device work as a pump. The realizable k–ε turbulence model was used. The performance parameters of the pump were assessed by considering the dimensionless flow coefficient and efficiency.
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Mohammadpour, Mahdi, Stephanos Theodossiades et Homer Rahnejat. « Tribo-Dynamics of Differential Hypoid Gears ». Dans ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12890.

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Differential hypoid gears play an important role on the Noise, Vibration and Harshness (NVH) signature of vehicles. Additionally, friction developed between their teeth flanks under extreme loading conditions adds another source of power loss in the drivetrain which can mitigate vibrational energy. The paper considers the coupling between dynamics and analytical tribology to study dynamic response of hypoid gear pairs with lateral motion of support shafts also included in the analysis framework. Friction of teeth flank pairs is assumed to follow elastohydrodynamic lubrication under elliptical point contact geometry with lubricant film behavior conforming to Non-Newtonian thermal shear, also with surface asperity interactions. Tooth Contact Analysis (TCA) has been used to obtain the input data required for the investigation. The dynamic behavior and efficiency of a differential hypoid gear pair under realistic operating conditions is determined. The proposed tribo-dynamic framework provides a useful platform to conduct an extensive series of parametric studies.
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9

Patterson, Edward M., David W. Roberts et Gary G. Gimmestad. « Atmospheric measurements using an eyesafe Raman-shifted lidar ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.thl5.

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We have developed an eyesafe lidar system for tropospheric cloud and aerosol studies using the Raman-shifted output from a Nd:YAG laser as the lidar source. The Nd:YAG beam pumps a cell containing methane at high pressure which undergoes stimulated Raman scattering, producing 1.54-μm pulses. The output beam is then expanded to produce an eyesafe beam at the output of the transmitter. The receiver unit consists of a 40-cm Newtonian telescope with a telecompressor to reduce the effective focal length of the telescope. The backscatter return is detected with an In-GaAs photodiode followed with a GaAs FET low noise preamplifier. The preamplifier output is digitized using a 20-MHz transient recorder. The transient recorder output is recorded using an IBM PC-AT computer, which also performs data analysis. To date, we have measured cirrus back scatter from 11-km altitude and aerosol return from ranges of more than 4 km. Measured system performance approximately matches that expected from a system analysis. Our results indicate that this Raman-shifted lidar has the sensitivity to be a useful tool for measurements of aerosols and clouds.
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10

Lamb, Sarah, Patricia Mellodge, Kiwon Sohn et Akin Tatoglu. « Control Analysis of a 3D Self-Balancing Inverted Pendulum and Cart System for Stability in the Event of a Sensor Failure ». Dans ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87586.

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This paper studies and simulates the dynamics and controls for a two-wheeled robotic chassis that successfully and consistently self-balances. Previous approaches to similar models have derived their dynamics from first principles using Newtonian mechanics for a linearized, shared-axle system and Lagrangian mechanics for a linearized, independently-actuated system. As such, the derived dynamics do not often reflect important factors of real world models which are not linear. However, this study specifically focuses on a more complicated system with independently-actuated wheels, for which a sophisticated and realistic dynamic model is derived using non-linearized Lagrangian mechanics. The pendulum and cart movements are each assumed to be planar, and their planes of motion are defined perpendicular to each other. The system’s performance is then analyzed in the simulation environment to determine the effect of various controllers and filters in cases of full and partial state feedback with and without sensor noise. Performance is characterized in terms of pendulum angle relative to the vertical axis and cart trajectory relative to the ground plane, both of which are functions of the voltage-applied force on each wheel independently. A comparison of the results shows that the non-linearized Lagrangian model best fits the true data and yields less uncertainty given a sensor failure. Therefore, the presented study has high intellectual merits compared to existing studies which focus on only linearized models. Based on the deterministic parameters of this study’s non-linearized model, a recommendation is made about which combination of controllers and filters best maintains the system’s stability in the event of a sensor failure returning only partial state feedback.
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