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Three-Axis Magnetometer Calibration Using Total Least Squares

JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2021年第8期44卷 1410-1424页

作者： Crassidis, John L. Cheng, Yang Univ Buffalo State Univ New York Dept Mech & Aerosp Engn Amherst NY 14260 USA Mississippi State Univ Dept Aerosp Engn Mississippi State MS 39762 USA

In this paper attitude-independent three-axis magnetometer (TAM) sensor calibration algorithms are presented from a total least squares approach. One algorithm estimates biases only, whereas the other performs full calibration, which includes biases, scale factors, and nonorthogonality corrections. All calibration parameters are assumed to be constant. It is shown that the TAM calibration problem using a standard least squares point of view is statistically inconsistent because the effective measurement variance is a function of the calibration parameters. This inconsistency is overcome by using the total least squares formulation. The error covariance of the calibration parameters is also derived, which is shown to be equivalent to the standard least squares formation to within first-order terms. Also, the covariance of the measurement-to-estimate residual vector is derived, which cannot be accomplished using a standard least squares approach. This covariance is useful to quantify the effects of the measurement covariance for attitude determination in real-world situations. Both simulated and experimental results are shown to assess the performance of the TAM calibration algorithms, as well as the derived covariance expressions.

关键词： Three Axis Magnetometer Sensors Transition Region and Coronal Explorer Lagrange Multipliers Earth probability density functions Binomial Expansion Geomagnetic Field Computing Small Satellites

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Prediction of acid rock drainage in waste rock piles part 2: Water flow patterns and leaching process

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JOURNAL OF CONTAMINANT HYDROLOGY 2021年 242卷 103862-103862页

作者： Ma, Liang Huang, Cheng Liu, Zhong-Sheng Morin, Kevin A. Aziz, Mike Meints, Cody Natl Res Council Canada Energy Min & Environm Res Ctr 4250 Wesbrook Mall Vancouver BC V6T 1W5 Canada Minesite Drainage Assessment Grp Surrey BC Canada Newmont Goldcorp Inc Equ Silver Mine Reclamat Operat POB 1450 Houston BC V0J 1Z0 Canada

In waste rock piles, the leaching process involved in acid rock drainage is mainly controlled by water flow. This paper (Part 2) investigates the effects of heterogeneities on the water flow patterns by applying probability density functions to hydrogeological properties. In this study, a piecewise constant distribution is proposed to describe the permeability inside waste rock piles, which reflects the effect of both finer and coarser pores. Compared with uniform water flow obtained from traditional homogeneous modeling, various water flow pat-terns and their pathways inside waste rock piles can be simulated by the proposed model. In addition, the leaching process is also investigated by coupling the calculated water flow with the geochemical reaction based on the water film model proposed in part 1. For demonstration, these models are integrated and applied to the full-scale waste rock pile at Equity Silver mine in British Columbia, Canada. Because the iron loading is highly correlated to the acidity at this site, it is found that the fluctuation of annual lime consumption for neutralization at this site can be well predicted by the integrated model. In addition, the results indicate that waste rock piles with different spatial patterns of permeability distribution, but with the same probability density function, may have different water flow patterns and spatial distributions of iron concentrations inside the pile. However, the total water flow discharge rate and iron loading profiles from the pile are almost the same on the temporal scale.

关键词： Acid rock drainage Waste rock pile Heterogeneity probability density functions Water flow pattern Leaching process

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Robust Space Trajectory Design using Belief Stochastic Optimal Control

Robust Space Trajectory Design using Belief Stochastic Optim...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Greco, Cristian Campagnola, Stefano Vasile, Massimiliano Univ Strathclyde Aerosp Ctr Excellence Glasgow G1 1XJ Lanark Scotland CALTECH Jet Prop Lab Outer Planet Mission Anal Grp Pasadena CA 91109 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

This paper presents a belief-based formulation and a novel approach for the robust solution of optimal control problems under uncertainty. The introduced formulation, based on the Belief Markov Decision Process model, reformulates the control problem directly in terms of uncertainty distributions, called beliefs, rather than on realisations of the system state. Successively, an approach inspired by navigation analysis is developed to transcribe and solve such problem in the presence of observation windows, employing a polynomial expansion for the dynamical propagation. Finally, the developed method is applied to the robust optimisation of a flyby trajectory of Europa Clipper mission in a scenario characterised by knowledge, execution and observation errors.

关键词： Stochastic Optimal Control Trajectory Optimization Callisto Markov Decision Process Orbit Determination Monte Carlo Sampling Techniques probability density functions Kalman Filter Apocenter Propellant

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Adaptive Confidence Filter Update for High Uncertainty Environments

Adaptive Confidence Filter Update for High Uncertainty Envir...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Fritsch, Gunner S. DeMars, Kyle J. Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

It is known that the commonly used extended Kalman filter (EKF) is prone to divergence in the presence of large updates. In light of the demands of upcoming spaceflight missions, this paper proposes a confidence-based method as an alternative for estimation in highly uncertain environments. In order to test the effectiveness of the proposed update, simulations are created wherein the performance of the proposed update is compared to an EKF equipped with an underweighting scheme, as well as to a second order EKF. Results of the simulations indicate the confidence-based filter as being more robust in select cases than the underweighted filter, without being overly conservative.

关键词： Extended Kalman Filter Spaceflight Missions Taylor Series Spacecraft Navigation Nonlinear Systems Monte Carlo Simulation probability density functions Clohessy Wiltshire Equation Kullback Leibler Divergence Information Processing

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Bubble Bifurcation in a Closed, Liquid-Filled Cylinder

Bubble Bifurcation in a Closed, Liquid-Filled Cylinder

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AIAA Propulsion and Energy Forum

作者： Obenauf, Dayna G. Halls, Benjamin R. Kunzler, W. Marley Farias, Paul A. Torczynski, John R. Sandia Natl Labs Engn Sci Ctr Albuquerque NM 87185 USA

ISBN: (数字)9781624106026

ISBN: (纸本)9781624106026

When subject to certain harmonic oscillations, the gas bubble in a partially liquid-filled, closed vertical cylinder will break up. Under certain conditions some of the gas will migrate to the bottom due to Bjerknes forces. At sufficiently large amplitudes, the bubble will fully bifurcate, yielding gas bubbles at the top and bottom ends of the cylinder. High-speed imaging captured the dynamics of the bubble breakup, the gas migration, and the resulting system with two gas regions. Several parameters were investigated: oscillation frequency, oscillation acceleration, gas volume fraction, and liquid viscosity.

关键词： Viscosity Harmonic Oscillation Sauter Mean Diameter Buoyancy Force Heat and Mass Transfer Quasi Steady States Propellant probability density functions Navier Stokes Equations Track Algorithm

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Assessment of Surrogate Models for Inverse Uncertainty Quantification of Simulant Combustion

Assessment of Surrogate Models for Inverse Uncertainty Quant...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Ranjan, R. Karpe, S. Patel, P. Menon, S. Univ Tennessee Chattanooga Dept Mech Engn 615 McCallie Ave Chattanooga TN 37403 USA Georgia Inst Technol Sch Aerosp Engn 270 Ferst Dr Atlanta GA 30332 USA

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Incineration of organophosphorus simulants at high-temperature conditions is an effective method for the destruction of chemical warfare agents. However, uncertainties associated with the behavior of simulant combustion pose a significant challenge to develop reliable destruction strategies. Inverse uncertainty quantification (UQ) is an effective computational approach to quantify the input parameters uncertainty for available measured data from experimental studies of simulant combustion. A non-intrusive Bayesian framework for inverse UQ of chemically reacting flows is desirable for its simplicity, where inverse UQ can be performed either using direct or surrogate modeling techniques. While the direct modeling approach is popular, it tends to be computationally prohibitive when it comes to the investigation of reacting flows in practical systems. To this end, surrogate modeling techniques offer a computationally tractable approach, but they need to be established for such studies. In this study, three surrogate approaches, namely, polynomial chaos expansion (PCE), stochastic collocation (SC), and Gaussian process (GP) are first assessed for their predictive capabilities for inverse UQ of a freely propagating laminar premixed flame by comparing with the results obtained from using the direct Markovian Chain Monte Carlo sampling (MCMC) technique. Based on the results, two surrogate approaches, namely, PCE and GP are then used to conduct inverse UQ of oxidation of diisopropyl methyl phosphonate (DIMP), a representative sarin simulant, in a shock tube setup. The results demonstrated the accuracy and efficiency aspects of surrogate modeling techniques for inverse UQ of simulant combustion.

关键词： Numerical Integration Shock Tube Laminar Flame Speed probability density functions Chemically Reacting Flow Chemical Warfare Pre Exponential Factor Artificial Neural Network Open Source Software Inverse Problems

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Liquid Jet Interaction with Supersonic Crossflow

Liquid Jet Interaction with Supersonic Crossflow

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Singh, Vishal Joseph, Nithin Chandy Thakor, Nimesh Chaudhuri, Swetaprovo Indian Inst Sci Dept Aerosp Engn Bengaluru India Univ Toronto Inst Aerosp Studies Toronto ON Canada

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

Experiments were performed to study the evolution of a liquid jet from a customized injector with nozzle exit diameter of 1 mm, injected transversely into a supersonic crossflow of M-infinity=2.2. High-speed shadowgraphy, using a high-frequency nano-pulsed laser, LED, and a high-speed camera is used to capture and study the spray features, especially the ligaments formed on the spray periphery. These ligaments were tracked in consecutive images with the help of normxcorr2 (an inbuilt Matlab function) to find their speed. Fundamental questions on ligament formation, motion, and their breakup are addressed. The penetration of the spray was evaluated by averaging out edge positions of the spray, which was detected using a canny edge detection algorithm, over thousands of images. Spray trajectory was estimated for three different values of momentum flux ratio (q).

关键词： MATLAB Freestream Conditions Shock Front Weber Number Supersonic Flow Stagnation Temperature Mass Flow Rate Combustors Liquid Fuels probability density functions

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Transforming Ground and Flight Testing through Digital Engineering

Transforming Ground and Flight Testing through Digital Engin...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech)

作者： Kraft, Edward M. Independent Consultant

ISBN: (数字)9781624105951

ISBN: (纸本)9781624105951

The ongoing global digital revolution is transforming all aspects of product development, delivery, operation, and support. Driven by cyber-physical technologies such as the Internet of Things (IoT), Cloud Computing, Big Data Analytics, Digital Engineering, and Digital Manufacturing it enables transforming current document-centric processes to a digital, connected, model-based systems engineering environment involving all the advances of the new cyber-physical world. Concepts for transforming ground and flight testing of aeronautical systems employing digital engineering principles and practices are introduced. A value metric for testing based on the quantification and planned mitigation of uncertainty of technical performance measures (TPM) is introduced. Traditional model validation by comparing model output with experimental data is transformed into an improved predictive capability using an integrated validation and calibration process for a digital surrogate response surface model using all heterogeneous data available. Approaches to using quantified margins and uncertainties for TPMs derived from calibrated digital surrogates to project the best way to master risk and reduce the time to achieve an operational capability are also presented. Concepts for digital engineering-enabled innovative approaches to air vehicles development and operation are outlined.

关键词： Flight Testing Model Based System Engineering Commercial Aircraft Surface Modeling Cloud Computing Big Data Analytics Wind Tunnel Tests Surrogate Model probability density functions Aerodynamic Coefficients

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Characterizing the multidimensionality of microplastics across environmental compartments

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WATER RESEARCH 2021年 202卷 117429-117429页

作者： Kooi, Merel Primpke, Sebastian Mintenig, Svenja M. Lorenz, Claudia Gerdts, Gunnar Koelmans, Albert A. Wageningen Univ & Res Aquat Ecol & Water Qual Management Grp Wageningen Netherlands Helmholtz Ctr Polar & Marine Res Alfred Wegener Inst Shelf Seas Syst Ecol Bremerhaven Germany Aalborg Univ Dept Built Environm Thomas Manns Vej 23 DK-9220 Aalborg Denmark

Understanding the multidimensionality of microplastics is essential for a realistic assessment of the risks these particles pose to the environment and human health. Here, we capture size, shape, area, polymer, volume and mass characteristics of >60,000 individual microplastic particles as continuous distributions. Particles originate from samples taken from different aquatic compartments, including surface water and sediments from the marine and freshwater environment, waste water effluents, and freshwater organisms. Data were obtained using state-ofthe-art FTIR-imaging, using the same automated imaging post-processing software. We introduce a workflow with two quality criteria that assure minimum data quality loss due to volumetric and filter area subsampling. We find that probability density functions (PDFs) for particle length follow power law distributions, with median slopes ranging from 2.2 for marine surface water to 3.1 for biota samples, and that these slopes were compartment-specific. Polymer-specific PDFs for particle length demonstrated significant differences in slopes among polymers, hinting at polymer specific sources, removal or fragmentation processes. Furthermore, we provide PDFs for particle width, width to length ratio, area, specific surface area, volume and mass distributions and propose how these can represent the full diversity of toxicologically relevant dose metrics required for the assessment of microplastic risks.

关键词： Microplastics probability density functions Size distribution Risk assessment Environment Human health

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Hurst Exponents for Intra- and Intercycle Thermoacoustic Oscillations

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JOURNAL OF PROPULSION AND POWER 2021年第4期37卷 553-563页

作者： Yi, Tongxun Fugger, Christopher Caswell, Andrew W. Roy, Sukesh Spectral Energies LLC 4065 Execut Drive Beavercreek OH 45430 USA US Air Force Res Lab 2130 Eighth St Dayton OH 45433 USA

The detrended fluctuation analysis, a technique for detecting long-range correlations in fractal time series, is used to characterize thermoacoustic oscillations of impending combustion instabilities. The slope of the linear regime of the structure function with respect to the time scale in a logarithmic plot, referred to as the Hurst exponent, takes a different value across a critical time scale corresponding to one pressure cycle. The slope for pressure oscillations over one pressure cycle, termed as the intercycle Hurst exponent, is a power-law scaling parameter for long-range oscillations;however, the slope for pressure oscillations within one pressure cycle, termed as the "intracycle Hurst exponent," is no longer a power-law scaling parameter but resultant from the nonstationary, local average of highly nonlinear (as a function of time), seemingly sinusoidal, nearly periodic pressure oscillations. Both parametric studies and analyses of experimental data show that the intracycle Hurst exponent consistently increases with the signal-to-noise ratio and peaks at 1.6, thus having potentials for assessments of the safety margin to the onset of combustion instabilities. Given the same observation window, the measurement error (or uncertainty) of the intracycle Hurst exponent is significantly lower than that of the intercycle Hurst exponent.

关键词： Combustion Instability Resonant Frequencies probability density functions Combustion Noise Rocket Engine Combustors Aircraft Engines White Noise Combustion Chambers Quasi Steady States

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