A simulated global GM estimate of the asteroid 469219 Kamo‘oalewa for China’s future asteroid mission

2020 ◽  
Vol 493 (3) ◽  
pp. 4012-4021 ◽  
Author(s):  
W T Jin ◽  
F Li ◽  
J G Yan ◽  
T P Andert ◽  
M Ye ◽  
...  
Keyword(s):  
Software Package ◽  
Initial Conditions ◽  
Weighted Least Squares ◽  
Reliable Estimate ◽  
Distance Measurements ◽  
Radio Science ◽  
Least Squares Fit ◽  
Asteroid Mission ◽  
Sample Return Mission ◽  
Simulation Results

ABSTRACT China will launch in the forthcoming years a sample return mission called ZhengHe, to asteroid 469219 Kamo‘oalewa (provisional designation 2016HO3) and comet 133P/Elst-Pizarro. The mission will consist of an orbiter and a nano-lander. One of ZhengHe’s investigations is the radio science experiment, whose main objective is the asteroid GM estimate. In this paper, we conduct full numerical simulations of the radio science experiment using the wudogs software package, developed by Wuhan University. In addition to two-way Doppler measurements, we also include one-way on-board distance measurements. A list of parameters including the spacecraft initial conditions and the global asteroid GM are solved using a weighted least-squares fit. The simulation results indicate that the GM solution is very sensitive to the ephemeris error. We need an accuracy within 2 km on the ephemeris of the asteroid to achieve a reliable estimate of GM.

A Geometric Theory for Form, Profile and Orientation Tolerances: Evaluation Algorithms and Simulation Results

1998 ◽  
Author(s):  
J. B. Gou ◽  
Y. X. Chu ◽  
Z. X. Li
Keyword(s):  
Minimization Problem ◽  
Software Package ◽  
Initial Conditions ◽  
Geometric Theory ◽  
Simulation Experiments ◽  
Extensive Simulation ◽  
Minimum Zone ◽  
Linear Programming Problems ◽  
Simulation Results ◽  
Tolerance Verification

Abstract Using the geometric theory for formulation of form, profile and orientation tolerances, we develop a simple geometric algorithm, called the Symmetric Minimum Zone (SMZ) algorithm, to unify the computation of form, profile and orientation tolerances. First, using a technique of numerical analysis, we transform the non-differentiable minimization problem into a differentiable minimization problem over an extended configuration space. Then, we solve the latter problem by computing the solutions of a sequence of linear programming problems which can be easily derived using the geometric properties of SE(3)/G0. The SMZ algorithm is incorporated into a software package called GTPack for tolerance verification. Numerous simulation experiments show that the SMZ algorithm has several important features which could lead to its rapid acceptance in the industry: (1) consistency with the Y14.5M standard, (2) computational efficiency, (3) robustness with respect to variations in initial conditions; and (4) implementational simplicity. We also give extensive simulation results comparing the performances of the SMZ algorithm against the best known algorithms in the literature.

Dynamics of the macromolecular composition of the biomass of microalgae in the morning under natural light. Model

2020 ◽  
pp. 45-52
Author(s):  
Alexander S. Lelekov ◽  
Anton V. Shiryaev
Keyword(s):  
Biochemical Composition ◽  
Initial Conditions ◽  
Natural Light ◽  
Photoautotrophic Growth ◽  
Structural Part ◽  
Basic Model ◽  
Microalgae Culture ◽  
Simulation Results ◽  
Structural Parts ◽  
Macromolecular Composition

The work is devoted to modeling the growth of optically dense microalgae cultures in natural light. The basic model is based on the idea of the two-stage photoautotrophic growth of microalgae. It is shown that the increase in the intensity of sunlight in the first half of the day can be described by a linear equation. Analytical equations for the growth of biomass of microalgae and its macromolecular components are obtained. As the initial conditions, it is assumed that at the time of sunrise, the concentration of reserve biomass compounds is zero. The simulation results show that after sunrise, the growth of the microalgae culture is due only to an increase in the reserve part of the biomass, while the structural part practically does not change over six hours. Changes in the ratio of the reserve and structural parts of the biomass indicate a change in the biochemical composition of cells.

scholarly journals Simulations of Switchback, Fragmentation and Sunspot Pair in δ-Sunspots during Magnetic Flux Emergence

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 586
Author(s):  
Che-Jui Chang ◽  
Jean-Fu Kiang
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Field Strength ◽  
Magnetic Flux ◽  
Initial Conditions ◽  
Observation Data ◽  
Flux Emergence ◽  
Polarity Inversion ◽  
Simulation Results ◽  
Spot Type

Strong flares and coronal mass ejections (CMEs), launched from δ-sunspots, are the most catastrophic energy-releasing events in the solar system. The formations of δ-sunspots and relevant polarity inversion lines (PILs) are crucial for the understanding of flare eruptions and CMEs. In this work, the kink-stable, spot-spot-type δ-sunspots induced by flux emergence are simulated, under different subphotospheric initial conditions of magnetic field strength, radius, twist, and depth. The time evolution of various plasma variables of the δ-sunspots are simulated and compared with the observation data, including magnetic bipolar structures, relevant PILs, and temperature. The simulation results show that magnetic polarities display switchbacks at a certain stage and then split into numerous fragments. The simulated fragmentation phenomenon in some δ-sunspots may provide leads for future observations in the field.

scholarly journals Limits of reproducibility and hydrodynamic noise in atmospheric regional modelling

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Beate Geyer ◽  
Thomas Ludwig ◽  
Hans von Storch
Keyword(s):  
Regional Climate Model ◽  
Computer Architecture ◽  
Climate Model ◽  
Initial Conditions ◽  
Regional Climate ◽  
Quality Criterion ◽  
Dynamic State ◽  
Regional Modelling ◽  
Simulation Results ◽  
Mathematical Operations

AbstractReproducibility of research results is a fundamental quality criterion in science; thus, computer architecture effects on simulation results must be determined. Here, we investigate whether an ensemble of runs of a regional climate model with the same code on different computer platforms generates the same sequences of similar and dissimilar weather streams when noise is seeded using different initial states of the atmosphere. Both ensembles were produced using a regional climate model named COSMO-CLM5.0 model with ERA-Interim forcing. Divergent phase timing was dependent on the dynamic state of the atmosphere and was not affected by noise seeded by changing computers or initial model state variations. Bitwise reproducibility of numerical results is possible with such models only if everything is fixed (i.e., computer, compiler, chosen options, boundary values, and initial conditions) and the order of mathematical operations is unchanged between program runs; otherwise, at best, statistically identical simulation results can be expected.

scholarly journals Extended and Unscented Kalman Filtering Applied to a Flexible-Joint Robot with Jerk Estimation

2010 ◽  
Vol 2010 ◽  
pp. 1-14 ◽  
Author(s):  
Mohammad Ali Badamchizadeh ◽  
Iraj Hassanzadeh ◽  
Mehdi Abedinpour Fallah
Keyword(s):  
Initial Conditions ◽  
Covariance Matrices ◽  
Flexible Joints ◽  
Velocity Measurements ◽  
Lagrange Equations ◽  
Robust Nonlinear Control ◽  
Flexible Joint ◽  
Flexible Joint Robots ◽  
Simulation Results

Robust nonlinear control of flexible-joint robots requires that the link position, velocity, acceleration, and jerk be available. In this paper, we derive the dynamic model of a nonlinear flexible-joint robot based on the governing Euler-Lagrange equations and propose extended and unscented Kalman filters to estimate the link acceleration and jerk from position and velocity measurements. Both observers are designed for the same model and run with the same covariance matrices under the same initial conditions. A five-bar linkage robot with revolute flexible joints is considered as a case study. Simulation results verify the effectiveness of the proposed filters.

scholarly journals Numerical Analysis of the Transport and Fate of Nitrate in the Soil and Nitrate Leaching to Drains

2001 ◽  
Vol 1 ◽  
pp. 170-180 ◽  
Author(s):  
Alaa El-Sadek ◽  
Mona Radwan ◽  
Jan Feyen
Keyword(s):  
Nitrate Leaching ◽  
Initial Conditions ◽  
Continuous Cropping ◽  
Nitrogen Transport ◽  
State Variables ◽  
Nitrogen Application ◽  
Transport And Transformation ◽  
Bottom Boundary Condition ◽  
Rainfall Depth ◽  
Simulation Results

In this study, the transport and fate of nitrate within the soil profile and nitrate leaching to drains were analyzed by comparing historic field data with the simulation results of the DRAINMOD model. The nitrogen version of DRAINMOD was used to simulate the performance of the nitrogen transport and transformation of the Hooibeekhoeve experiment, situated in the sandy region of the Kempen (Belgium) and conducted for a 30-year (1969–1998) period. In the analysis, a continuous cropping with maize was assumed. Comparisons between experimentally measured and simulated state variables indicate that the nitrate concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions, and the rainfall depth and distribution. Furthermore, the study reveals that the model used gives a fair description of the nitrogen dynamics in the soil and subsurface drainage at field scale. From the comparative analysis between experimental data and simulation results it can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting in an acceptable level of nitrate leaching for the environment.

scholarly journals High resolution general purpose D-layer experiment for EISCAT incoherent scatter radars using selected set of random codes

2002 ◽  
Vol 20 (9) ◽  
pp. 1469-1477 ◽  
Author(s):  
T. Turunen ◽  
A. Westman ◽  
I. Häggström ◽  
G. Wannberg
Keyword(s):  
Autocorrelation Function ◽  
Spatial Resolution ◽  
Measurement Problem ◽  
Short Pulse ◽  
Plasma Temperature ◽  
General Purpose ◽  
Reliable Estimate ◽  
Radio Science ◽  
Coherent Integration ◽  
Random Codes

Abstract. The ionospheric D-layer is a narrow bandwidth radar target often with a very small scattering cross section. The target autocorrelation function can be obtained by transmitting a series of relatively short coded pulses and computing the correlation between data obtained from different pulses. The spatial resolution should be as high as possible and the spatial side lobes of the codes used should be as small as possible. However, due to the short pulse repetition period (in the order of milliseconds) at any instant, the radar receives detectable scattered signals not only from the pulse illuminating the D-region but also from 3–5 ambiguous-range pulses, which makes it difficult to produce a reliable estimate near zero lag of the autocorrelation function. A new experimental solution to this measurement problem, using a selected set of 40-bit random codes with 4 µs elements giving 600 m spatial resolution is presented. The zero lag is approximated by dividing the pulse into two 20-bit codes and computing the correlation between those two pulses. The lowest altitudes of the E-layer are measured by dividing the pulse into 5 pieces of 8 bits, which allows for computation of 4 lags. In addition, coherent integration of data from four pulses is used for obtaining separately the autocorrelation function estimate for the lowest altitudes and in cases when the target contains structures with a long coherence time. Design details and responses of the experiment are given, and analysed test data are shown.Key words. Radio science (signal processing); Ionosphere (plasma temperature and density; instruments and techniques)

scholarly journals STRESSING ISSUE OF A PIEZOCERAMIC CANTILEVER WITH LONGITUDINAL POLARISATION AND ELECTRODE COATINGS

2020 ◽  
Vol 19 (2) ◽  
pp. 113
Author(s):  
Igor Jovanović ◽  
Ljubiša Perić ◽  
Uglješa Jovanović ◽  
Dragan Mančić
Keyword(s):  
General Solution ◽  
Free Vibration ◽  
Electric Potential ◽  
Software Package ◽  
Longitudinal Polarization ◽  
Main Subject ◽  
Piezoceramic Material ◽  
Coupled Equations ◽  
Specific Strain ◽  
Simulation Results

The main subject of this study is the investigation of the free vibration of a rectangular prismatic piezoceramic cantilever with longitudinal polarization and electrode coatings. Based on the general solution of coupled equations for piezoceramic material, applying the equations of electro-elasticity and satisfying electrical and mechanical conditions for the stress of a cantilever made from PZT4 piezoceramic material, componential displacements, electric potential, specific strain, electric field, and piezoelectric displacement, are determined and numerically obtained with Matlab software package. Based on the obtained equations and simulation results, it is possible to optimize the dimensions of the cantilever and determine the type of piezoceramic.

scholarly journals A Robust Discontinuous Phase Unwrapping Based on Least-Squares Orientation Estimator

Electronics ◽  
2021 ◽  
Vol 10 (22) ◽  
pp. 2871
Author(s):  
Gaoxu Deng ◽  
Shiqian Wu ◽  
Shiyang Zhou ◽  
Bin Chen ◽  
Yucheng Liao
Keyword(s):  
Least Squares ◽  
Weighted Least Squares ◽  
Bilateral Filter ◽  
Phase Unwrapping ◽  
Noise Variance ◽  
Post Processing ◽  
Quadratic Error ◽  
Error Norm ◽  
Discontinuous Phase ◽  
Simulation Results

Weighted least-squares (WLS) phase unwrapping is widely used in optical engineering. However, this technique still has issues in coping with discontinuity as well as noise. In this paper, a new WLS phase unwrapping algorithm based on the least-squares orientation estimator (LSOE) is proposed to improve phase unwrapping robustness. Specifically, the proposed LSOE employs a quadratic error norm to constrain the distance between gradients and orientation vectors. The estimated orientation is then used to indicate the wrapped phase quality, which is in terms of a weight mask. The weight mask is calculated by post-processing, including a bilateral filter, STDS, and numerical relabeling. Simulation results show that the proposed method can work in a scenario in which the noise variance is 1.5. Comparisons with the four WLS phase unwrapping methods indicate that the proposed method provides the best accuracy in terms of segmentation mean error under the noisy patterns.

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