scholarly journals Impact hazard monitoring: theory and implementation

2015 ◽  
Vol 10 (S318) ◽  
pp. 221-230
Author(s):  
D. Farnocchia
Keyword(s):  
Hazard Assessment ◽  
Yarkovsky Effect ◽  
Monte Carlo Algorithms ◽  
Impact Monitoring ◽  
Successful Technique ◽  
Low Probability ◽  
Computationally Intensive ◽  
Orbit Estimation ◽  
Near Earth Asteroids ◽  
The Impact

AbstractWe review the most standard impact monitoring techniques. Linear methods are the fastest approach but their applicability regime is limited because of the chaotic dynamics of near-Earth asteroids. Among nonlinear methods, Monte Carlo algorithms are the most reliable ones but also most computationally intensive and so unpractical for routine impact monitoring. In the last 15 years, the Line of Variations method has been the most successful technique thanks to its computational efficiency and capability of detecting low probability events deep in the nonlinear regime. We also present some more recent techniques developed to deal with the new challenges arising in the impact hazard assessment problem. In particular, we describe keyhole maps as a tool to go beyond strongly scattering encounters and how to account for nongravitational perturbations, especially the Yarkovsky effect, when their contribution is the main source of prediction uncertainty. Finally, we discuss systematic ranging to deal with the short-term hazard assessment problem for newly discovered asteroids, when only a short observed arc is available thus leading to severe degeneracies in the orbit estimation process.

scholarly journals Yarkovsky effect detection and updated impact hazard assessment for near-Earth asteroid (410777) 2009 FD

2019 ◽  
Vol 627 ◽  
pp. L11
Author(s):  
A. Del Vigna ◽  
J. Roa ◽  
D. Farnocchia ◽  
M. Micheli ◽  
D. Tholen ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Dimensional Space ◽  
Semimajor Axis ◽  
Sampling Technique ◽  
Second Century ◽  
Force Model ◽  
Earth Asteroid ◽  
Yarkovsky Effect ◽  
The Impact ◽  
Astrometric Data

Aims. Near-Earth asteroid (410777) 2009 FD is a potentially hazardous asteroid with possible (though unlikely) impacts on Earth at the end of the twenty-second century. The astrometry collected during the 2019 apparition provides information on the trajectory of (410777) by constraining the Yarkovsky effect, which is the main source of uncertainty for future predictions, and improving the impact hazard assessment. Methods. We included the Yarkovsky effect in the force model and estimated its magnitude from the fit to the optical and radar astrometric data of (410777). We performed the hazard assessment for (410777) over 200 years using two independent approaches: the NEODyS group adopted a generalisation of the Line Of Variations method in a seven-dimensional space, and the JPL team used the Multi-Layer Clustered Sampling technique. Results. We obtain a 4σ detection of the Yarkovsky effect acting on (410777), which corresponds to a semimajor axis drift of (3.8 ± 0.9) × 10−3 au Myr−1. In the hazard results of both teams, the main impact possibility in 2185 is ruled out and the only remaining one is in 2190, but with a probability lower than 10−8.

scholarly journals Detecting the Yarkovsky effect among near-Earth asteroids from astrometric data

2018 ◽  
Vol 617 ◽  
pp. A61 ◽  
Author(s):  
A. Del Vigna ◽  
L. Faggioli ◽  
A. Milani ◽  
F. Spoto ◽  
D. Farnocchia ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Semimajor Axis ◽  
Solar Radiation Pressure ◽  
Yarkovsky Effect ◽  
Impact Monitoring ◽  
Data Volume ◽  
Near Earth Asteroids ◽  
Near Future ◽  
Astrometric Data ◽  
Impact Predictions

We present an updated set of near-Earth asteroids with a Yarkovsky-related semimajor axis drift detected from the orbital fit to the astrometry. We find 87 reliable detections after filtering for the signal-to-noise ratio of the Yarkovsky drift estimate and making sure the estimate is compatible with the physical properties of the analysed object. Furthermore, we find a list of 24 marginally significant detections for which future astrometry could result in a Yarkovsky detection. A further outcome of the filtering procedure is a list of detections that we consider spurious because they are either unrealistic or not explicable by the Yarkovsky effect. Among the smallest asteroids of our sample, we determined four detections of solar radiation pressure in addition to the Yarkovsky effect. As the data volume increases in the near future, our goal is to develop methods to generate very long lists of asteroids that have a Yarkovsky effect that is reliably detected and have limited amounts of case by case specific adjustments. Furthermore, we discuss the improvements this work could bring to impact monitoring. In particular, we exhibit two asteroids for which the adoption of a non-gravitational model is needed to make reliable impact predictions.

scholarly journals Deterministic approach for multiple-source tsunami hazard assessment for Sines, Portugal

2015 ◽  
Vol 15 (11) ◽  
pp. 2557-2568 ◽  
Author(s):  
M. Wronna ◽  
R. Omira ◽  
M. A. Baptista
Keyword(s):  
Sea Level ◽  
Wave Height ◽  
Hazard Assessment ◽  
Test Site ◽  
Tsunami Hazard ◽  
Deterministic Approach ◽  
Flow Depth ◽  
Mean Sea Level ◽  
Tsunami Hazard Assessment ◽  
The Impact

Abstract. In this paper, we present a deterministic approach to tsunami hazard assessment for the city and harbour of Sines, Portugal, one of the test sites of project ASTARTE (Assessment, STrategy And Risk Reduction for Tsunamis in Europe). Sines has one of the most important deep-water ports, which has oil-bearing, petrochemical, liquid-bulk, coal, and container terminals. The port and its industrial infrastructures face the ocean southwest towards the main seismogenic sources. This work considers two different seismic zones: the Southwest Iberian Margin and the Gloria Fault. Within these two regions, we selected a total of six scenarios to assess the tsunami impact at the test site. The tsunami simulations are computed using NSWING, a Non-linear Shallow Water model wIth Nested Grids. In this study, the static effect of tides is analysed for three different tidal stages: MLLW (mean lower low water), MSL (mean sea level), and MHHW (mean higher high water). For each scenario, the tsunami hazard is described by maximum values of wave height, flow depth, drawback, maximum inundation area and run-up. Synthetic waveforms are computed at virtual tide gauges at specific locations outside and inside the harbour. The final results describe the impact at the Sines test site considering the single scenarios at mean sea level, the aggregate scenario, and the influence of the tide on the aggregate scenario. The results confirm the composite source of Horseshoe and Marques de Pombal faults as the worst-case scenario, with wave heights of over 10 m, which reach the coast approximately 22 min after the rupture. It dominates the aggregate scenario by about 60 % of the impact area at the test site, considering maximum wave height and maximum flow depth. The HSMPF scenario inundates a total area of 3.5 km2.

scholarly journals New Tools for the Optimized Follow-Up of Imminent Impactors

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Maddalena Mochi ◽  
Giacomo Tommei
Keyword(s):  
Orbit Determination ◽  
Main Belt ◽  
Impact Monitoring ◽  
The Earth ◽  
Current Observation ◽  
Short Period ◽  
Fly Eye ◽  
Near Earth Asteroids ◽  
Near Earth Objects

The solar system is populated with, other than planets, a wide variety of minor bodies, the majority of which are represented by asteroids. Most of their orbits are comprised of those between Mars and Jupiter, thus forming a population named Main Belt. However, some asteroids can run on trajectories that come close to, or even intersect, the orbit of the Earth. These objects are known as Near Earth Asteroids (NEAs) or Near Earth Objects (NEOs) and may entail a risk of collision with our planet. Predicting the occurrence of such collisions as early as possible is the task of Impact Monitoring (IM). Dedicated algorithms are in charge of orbit determination and risk assessment for any detected NEO, but their efficiency is limited in cases in which the object has been observed for a short period of time, as is the case with newly discovered asteroids and, more worryingly, imminent impactors: objects due to hit the Earth, detected only a few days or hours in advance of impacts. This timespan might be too short to take any effective safety countermeasure. For this reason, a necessary improvement of current observation capabilities is underway through the construction of dedicated telescopes, e.g., the NEO Survey Telescope (NEOSTEL), also known as “Fly-Eye”. Thanks to these developments, the number of discovered NEOs and, consequently, imminent impactors detected per year, is expected to increase, thus requiring an improvement of the methods and algorithms used to handle such cases. In this paper we present two new tools, based on the Admissible Region (AR) concept, dedicated to the observers, aiming to facilitate the planning of follow-up observations of NEOs by rapidly assessing the possibility of them being imminent impactors and the remaining visibility time from any given station.

scholarly journals The Impact of Water Loss by Evaporation and Calcite Precipitation on the Sodium Adsorption Ratio (SAR) and an Alternative Method of Estimating the SAR of Irrigation Drainage Water

2020 ◽  
Author(s):  
Qiyu Zhou ◽  
William Bleam ◽  
Douglas Soldat
Keyword(s):  
Hazard Assessment ◽  
Water Loss ◽  
Irrigation Water ◽  
Drainage Water ◽  
Sodium Adsorption Ratio ◽  
Calcite Precipitation ◽  
Water Composition ◽  
Soluble Calcium ◽  
Irrigation Drainage ◽  
The Impact

Soil water loss by evaporation influences the sodium adsorption ratio (SAR) of irrigation drainage water. Evaporation concentrates sodium and magnesium but calcite precipitation has a more complicated effect on soluble calcium and alkalinity. Here we propose a revised sodicity hazard assessment that quantifies the impact of evaporative water loss and calcite precipitation on drainage water SAR. This paper shows sodicity hazard is determined by the initial composition of irrigation water as originally suggested by previous researchers, and provide a simple, accurate way to identify the potential sodicity hazard of any irrigation water. In particular, the initial equivalent concentration of alkalinity and calcium determine the salinization pathway followed during evaporation. If the irrigation water alkalinity exceeds soluble calcium expressed as equivalent concentrations, drainage water SAR approaches an upper limit determined by the initial relative concentration of sodium and magnesium. If irrigation water alkalinity is less than soluble calcium, drainage water SAR approaches a lower limit determined by the initial calcium, magnesium and sodium. In both cases the SAR is scaled by the square root of the concentration factor √Fc quantifying soil water loss. To assess the impact of evaporation and calcite precipitation on the SAR and test the accuracy of the new sodicity hazard assessment, we evaluated data from previously published lysimeter studies. We plotted water composition boundaries for each source water, comparing these boundaries to the drainage water composition recorded in the lysimeter studies. As salinity increased by evaporation, each drainage water followed a distinct salinization path.

scholarly journals Influence of non-gravitational effects on the Centaur upper stage of the Surveyor 2 spacecraft

2021 ◽  
Vol 2103 (1) ◽  
pp. 012029
Author(s):  
A A Martyusheva ◽  
A V Devyatkin
Keyword(s):  
Solar Radiation Pressure ◽  
Close Approach ◽  
Major Axis ◽  
Semi Major Axis ◽  
Maximum Displacement ◽  
Gravitational Effects ◽  
Yarkovsky Effect ◽  
Upper Stage ◽  
The Impact ◽  
Heliocentric Orbit

Abstract A small near-Earth asteroid, discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) on September 17, 2020, turned out to be a part of the Centaur upper stage of the Surveyor 2 spacecraft launched by NASA on September 20, 1966 and subsequently crashed. This object had moved in a heliocentric orbit until it was under the influence of Earth’s gravitational field. As a result, a close approach to the Earth took place at a distance of about 50000 km on December 1, 2020. Despite the fact that the Centaur escaped back into a new orbit around the Sun in March 2021, it is of special interest for research, in particular, to consider the impact of non-gravitational effects on its orbital characteristics. Thus, it was calculated that the maximum displacement of the object trajectory due to the influence of solar radiation pressure over 15 years (the next close approach will take place in 2036) can be about 10.3-13.5 km, depending on the albedo. Estimations of the Yarkovsky effect showed that the magnitude of the expected change in the semi-major axis of Centaur’s orbit is from -8.1 • 10−13 to 1.6 10−13, depending on the angle of its rotation.

Metaheuristic- and Statistical-Based Sampling in Optimization

2018 ◽  
pp. 84-104
Author(s):  
Yoel Tenne
Keyword(s):  
Computer Simulations ◽  
Real World ◽  
Computational Intelligence ◽  
Numerical Experiments ◽  
Strong Impact ◽  
Initial Sample ◽  
Modern Engineering ◽  
Computationally Intensive ◽  
The Impact ◽  
Optimization Search

Modern engineering often uses computer simulations as a partial substitute to real-world experiments. As such simulations are often computationally intensive, metamodels, which are numerical approximations of the simulation, are often used. Optimization frameworks which use metamodels require an initial sample of points to initiate the main optimization process. Two main approaches for generating the initial sample are the ‘design of experiments' method which is statistically based, and the more recent metaheuristic-based sampling which uses a metaheuristic or a computational intelligence algorithm. Since the initial sample can have a strong impact on the overall optimization search and since the two sampling approaches operate based only widely different mechanisms this study analyzes the impact of these two approaches on the overall search effectiveness in an extensive set of numerical experiments which covers a wide variety of scenarios. A detailed analysis is then presented which highlights which method was the most beneficial to the search depending on the problem settings.

scholarly journals Sensor Distribution Optimization for Structural Impact Monitoring Based on NSGA-II and Wavelet Decomposition

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4264 ◽  
Author(s):  
Peng Li ◽  
Liuwei Huang ◽  
Jiachao Peng
Keyword(s):  
Wavelet Decomposition ◽  
Principal Component ◽  
Experimental System ◽  
Vibration Signal ◽  
The Finite Element Method ◽  
Nsga Ii ◽  
Impact Monitoring ◽  
Impact Location ◽  
Average Accuracy ◽  
The Impact

Optimal sensor placement is a significant task for structural health monitoring (SHM). In this paper, an SHM system is designed which can recognize the different impact location and impact degree in the composite plate. Firstly, the finite element method is used to simulate the impact, extracting numerical signals of the structure, and the wavelet decomposition is used to extract the band energy. Meanwhile, principal component analysis (PCA) is used to reduce the dimensions of the vibration signal. Following this, the non-dominated sorting genetic algorithm (NSGA-II) is used to optimize the placement of sensors. Finally, the experimental system is established, and the Product-based Neural Network is used to recognize different impact categories. Three sets of experiments are carried out to verify the optimal results. When three sensors are applied, the average accuracy of the impact recognition is 59.14%; when the number of sensors is four, the average accuracy of impact recognition is 76.95%.

scholarly journals The partial banana mapping: a robust linear method for impact probability estimation

2019 ◽  
Vol 492 (3) ◽  
pp. 4546-4552
Author(s):  
Dmitrii E Vavilov
Keyword(s):  
Coordinate System ◽  
Confidence Region ◽  
Linear Method ◽  
Probability Estimation ◽  
Curvilinear Coordinate System ◽  
The Earth ◽  
Curvilinear Coordinate ◽  
Near Earth Asteroids ◽  
The Impact ◽  
Confidence Ellipsoid

ABSTRACT This paper presents a robust linear method for impact probability estimation of near-Earth asteroids with the Earth. This method is a significantly modified and improved method, which uses a special curvilinear coordinate system associated with the nominal orbit of an asteroid. One of the coordinates of this system is the mean anomaly in the osculating orbit of an asteroid. A normal distribution of errors of coordinates and velocities of this system is assumed. Because of the usage of the curvilinear coordinate system, the fact that the confidence region is curved and stretched mainly along the nominal asteroid orbit is taken into account. On the main axis of the curvilinear confidence ellipsoid the virtual asteroid, which is the closest to the Earth, is found. The part of the curvilinear confidence ellipsoid, around the found virtual asteroid, is obtained and mapped on to its target plane. The impact probability is calculated as the probability of the asteroid being in the region of the found virtual asteroid multiplied by the probability of a collision of the found virtual asteroid with the Earth. This approach is shown to give more accurate and trustworthy results than the target plane method.

scholarly journals Assessment of Heating and Cooling of a Spontaneous Fire Source in Coal Deposits—Effect of Coal Grain Size

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 907
Author(s):  
Marek Więckowski ◽  
Natalia Howaniec ◽  
Adam Smoliński
Keyword(s):  
Carbon Monoxide ◽  
Hazard Assessment ◽  
Fire Hazard ◽  
Temperature Drop ◽  
Coal Bed ◽  
Coal Deposit ◽  
Fire Source ◽  
Heating And Cooling ◽  
Spontaneous Fire ◽  
The Impact

Fire hazard assessment in coal mines is performed on the basis of concentrations of particular gases emitted from the heating coal deposit, but more precise criteria and indicators are needed to assess fire hazard properly—both during the temperature rise phase and in the coal bed cooling phase. In the paper the impact of coal grinding on hazard assessment of spontaneous fire development in the coal deposit during heating and cooling the fire source was analyzed. The intensity of desorption of ethane, ethylene, propane, propylene, acetylene, carbon monoxide and hydrogen is the resultant of temperature and grinding of coal samples. The results proved that the ratio of concentrations emitted by standard versus coarsely crushed coal for each of the gases, changed both in the growth phase as well as in the temperature drop phase. It was found that as the temperature rose, the effect of coal grinding on the release of ethane, ethylene, propane, propylene and carbon monoxide decreased. The greatest effect of coal grinding was observed in the case of ethane and propane, while the lowest in the case of hydrogen and carbon monoxide.

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