Asteroid masses obtained with INPOP planetary ephemerides

2020 ◽  
Author(s):  
Agnes Fienga ◽  
Chrysa Avdellidou ◽  
Josef Hanus
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Sampling ◽  
New Method ◽  
Navigation Data ◽  
The Earth ◽  
Better Than ◽  
Juno Mission

<p>We present here masses of 103 asteroids deduced from their perturbations on the<br />orbits of the inner planets, in particular Mars and the Earth. These determinations and the<br />INPOP19a planetary ephemerides are improved by the recent Mars orbiter navigation data<br />and the updated orbit of Jupiter based on the Juno mission data. More realistic mass estimates<br />are computed by a new method based on random Monte-Carlo sampling that uses up-to-date<br />knowledge of asteroid bulk densities. We provide masses with uncertainties better than 33%<br />for 103 asteroids. Deduced bulk densities are consistent with those observed within the main<br />spectroscopic complexes.</p>

Asteroid masses obtained with INPOP planetary ephemerides

2019 ◽  
Vol 492 (1) ◽  
pp. 589-602 ◽  
Author(s):  
A Fienga ◽  
C Avdellidou ◽  
J Hanuš
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Sampling ◽  
New Method ◽  
Navigation Data ◽  
The Earth ◽  
Better Than ◽  
Juno Mission

ABSTRACT In this paper, we present masses of 103 asteroids deduced from their perturbations on the orbits of the inner planets, in particular Mars and the Earth. These determinations and the INPOP19a planetary ephemerides are improved by the recent Mars orbiter navigation data and the updated orbit of Jupiter based on the Juno mission data. More realistic mass estimates are computed by a new method based on random Monte Carlo sampling that uses up-to-date knowledge of asteroid bulk densities. We provide masses with uncertainties better than 33${{\ \rm per\ cent}}$ for 103 asteroids. Deduced bulk densities are consistent with those observed within the main spectroscopic complexes.

Bayesian Variational Seismic Tomography using Normalizing Flows

2021 ◽  
Author(s):  
Xuebin Zhao ◽  
Andrew Curtis ◽  
Xin Zhang
Keyword(s):  
Monte Carlo ◽  
Seismic Tomography ◽  
Computational Cost ◽  
Large Data ◽  
Optimization Methods ◽  
Monte Carlo Sampling ◽  
New Method ◽  
Posterior Probability Distribution ◽  
Computationally Expensive ◽  
A Chain

<p>Seismic travel time tomography is used widely to image the Earth's interior structure and to infer subsurface properties. Tomography is an inverse problem, and computationally expensive nonlinear inverse methods are often deployed in order to understand uncertainties in the tomographic results. Monte Carlo sampling methods estimate the posterior probability distribution which describes the solution to Bayesian tomographic problems, but they are computationally expensive and often intractable for high dimensional model spaces and large data sets due to the curse of dimensionality. We therefore introduce a new method of variational inference to solve Bayesian seismic tomography problems using optimization methods, while still providing fully nonlinear, probabilistic results. The new method, known as normalizing flows, warps a simple and known distribution (for example a Uniform or Gaussian distribution) into an optimal approximation to the posterior distribution through a chain of invertible transforms. These transforms are selected from a library of suitable functions, some of which invoke neural networks internally. We test the method using both synthetic and field data. The results show that normalizing flows can produce similar mean and uncertainty maps to those obtained from both Monte Carlo and another variational method (Stein varational gradient descent), at significantly decreased computational cost. In our tomographic tests, normalizing flows improves both accuracy and efficiency, producing maps of UK surface wave speeds and their uncertainties at the finest resolution and the lowest computational cost to-date, allowing results to be interrogated efficiently and quantitatively for subsurface structure.</p>

scholarly journals DETECTING CONVERGENCE CLUBS

2018 ◽  
Vol 24 (3) ◽  
pp. 629-669 ◽  
Author(s):  
Fuat C. Beylunioğlu ◽  
M. Ege Yazgan ◽  
Thanasis Stengos
Keyword(s):  
Monte Carlo ◽  
A Priori ◽  
Maximum Clique ◽  
Real Data ◽  
Maximal Clique ◽  
New Method ◽  
Monte Carlo Simulation Study ◽  
Income Differences ◽  
Convergence Clubs ◽  
Better Than

The convergence hypothesis, which is developed in the context of growth economics, asserts that the income differences across countries are transitory, and developing countries will eventually attain the level of income of developed ones. On the other hand, convergence clubs hypothesis claim that the convergence can only be realized across groups of countries that share some common characteristics. In this study, we propose a new method to find convergence clubs that combines a pairwise method of testing convergence with maximum clique and maximal clique algorithms. Unlike many of those already developed in the literature, this new method aims to find convergence clubs endogenously without depending on a-priori classifications. In a Monte Carlo simulation study, the success of the method in finding convergence clubs is compared with a similar algorithm. Simulation results indicated that the proposed method perform better than the compared algorithm in most cases. In addition to the Monte Carlo, a new empirical evidence on the existence of convergence clubs is presented in the context of real data applications.

scholarly journals Coupled Anharmonic Thermochemistry from Stratified Monte-Carlo Integration

2021 ◽  
Author(s):  
Gabriel Rath ◽  
Wassja Kopp ◽  
Kai Leonhard
Keyword(s):  
Monte Carlo ◽  
Gas Phase ◽  
Classical Method ◽  
Monte Carlo Sampling ◽  
Monte Carlo Integration ◽  
Anharmonic Corrections ◽  
Fully Coupled ◽  
Better Than ◽  
The Ideal

This study presents CIMCI, a new semi-classical method for handling fully coupled anharmonicity in gas-phase thermodynamics that promises to be black-boxable, to be<br>applicable for all kinds of anharmonicity, and to scale better at higher dimensionality than other methods for handling gas-phase molecular anharmonicity. The method<br>does so by using automatically and recursively stratified, simultaneous Monte Carlo integration of multiple functions. For the small systems analyzed by this study, the<br>method’s anharmonic corrections match reference data better than those of other blackbox anharmonic methods, e.g. VPT2. This holds even when sampling with CIMCI<br>is done with primitive force fields, e.g. UFF, while the competing methods are used with proper, comprehensive potentials, e.g. the M06-2X meta-hybrid DFT functional.<br>With further refinements in Monte Carlo sampling efficiency, in the quality of fast potentials practical for Monte Carlo sampling, and in automatic detection of which stereoisomers should be included during sampling, CIMCI has the potential to be the ideal anharmonic treatment for larger molecules where the large number of conformers<br>and the high dimensionality of coupled torsions present major difficulties for other, existing treatments for anharmonicity.<br>

scholarly journals Coupled Anharmonic Thermochemistry from Stratified Monte-Carlo Integration

2021 ◽  
Author(s):  
Gabriel Rath ◽  
Wassja Kopp ◽  
Kai Leonhard
Keyword(s):  
Monte Carlo ◽  
Gas Phase ◽  
Classical Method ◽  
Monte Carlo Sampling ◽  
Monte Carlo Integration ◽  
Anharmonic Corrections ◽  
Fully Coupled ◽  
Better Than ◽  
The Ideal

This study presents CIMCI, a new semi-classical method for handling fully coupled anharmonicity in gas-phase thermodynamics that promises to be black-boxable, to be<br>applicable for all kinds of anharmonicity, and to scale better at higher dimensionality than other methods for handling gas-phase molecular anharmonicity. The method<br>does so by using automatically and recursively stratified, simultaneous Monte Carlo integration of multiple functions. For the small systems analyzed by this study, the<br>method’s anharmonic corrections match reference data better than those of other blackbox anharmonic methods, e.g. VPT2. This holds even when sampling with CIMCI<br>is done with primitive force fields, e.g. UFF, while the competing methods are used with proper, comprehensive potentials, e.g. the M06-2X meta-hybrid DFT functional.<br>With further refinements in Monte Carlo sampling efficiency, in the quality of fast potentials practical for Monte Carlo sampling, and in automatic detection of which stereoisomers should be included during sampling, CIMCI has the potential to be the ideal anharmonic treatment for larger molecules where the large number of conformers<br>and the high dimensionality of coupled torsions present major difficulties for other, existing treatments for anharmonicity.<br>

UGR CALCULATION BASED ON THE LUMINANCE SPATIAL-ANGULAR DISTRIBUTION

2020 ◽  
Vol 2020 (4) ◽  
pp. 25-32
Author(s):  
Viktor Zheltov ◽  
Viktor Chembaev
Keyword(s):  
Monte Carlo ◽  
Angular Distribution ◽  
Monte Carlo Method ◽  
Visual Task ◽  
New Method ◽  
Lighting System ◽  
Preliminary Assessment ◽  
System A ◽  
The Monte Carlo Method

The article has considered the calculation of the unified glare rating (UGR) based on the luminance spatial-angular distribution (LSAD). The method of local estimations of the Monte Carlo method is proposed as a method for modeling LSAD. On the basis of LSAD, it becomes possible to evaluate the quality of lighting by many criteria, including the generally accepted UGR. UGR allows preliminary assessment of the level of comfort for performing a visual task in a lighting system. A new method of "pixel-by-pixel" calculation of UGR based on LSAD is proposed.

A Design of High-Accuracy Displacement Measurement Instrument from Principles of Optics

2012 ◽  
Vol 170-173 ◽  
pp. 2924-2928
Author(s):  
Sheng Biao Chen ◽  
Yun Zhi Tan
Keyword(s):  
Measurement Instrument ◽  
High Accuracy ◽  
Mechanical Tests ◽  
Total Reflection ◽  
Displacement Measurement ◽  
New Method ◽  
Water Volume ◽  
Water Drainage ◽  
Accuracy Of Measurement ◽  
Better Than

In order to measure the water drainage volume in soil mechanical tests accurately, it develop a new method which is based on principles of optics. And from both physical and mathematic aspects, it deduces the mathematic relationship between micro change in displacement and the increment projected on screen. The result shows that total reflection condition is better than refraction condition. What’s more, the screen could show the water volume micro variation clearly, so it can improve the accuracy of measurement.

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