Constraints on magma ascent and pressurisation prior to explosive paroxysms on Stromboli

2020 ◽  
Author(s):  
Mike Burton ◽  
Catherine Hayer ◽  
Giuseppe La Spina
Keyword(s):  
Closed System ◽  
Total Mass ◽  
Initial Conditions ◽  
Magma Ascent ◽  
Imaging Spectrometer ◽  
Rapid Ascent ◽  
The Common ◽  
Warning Time ◽  
Trajectory Modelling ◽  
Modelling Approach

<p>The paroxysmal eruptions of Stromboli in July and August 2019 highlighted with stark clarity the risks associated with visiting the summit of this remarkable volcano. It is an imperative for the volcanological community to recognise signals which precede such paroxysms, with the aim of maximising the warning time before an eruption. The common interpretation of the process driving paroxysms is that a volume of buoyant magma rises from depth, degassing in closed-system. The ascent is rapid, from 10 km depth to the surface in a few hours. This rapid ascent produces a kinetic limit to crystal growth, reflected in the ‘blonde’ colour of the eruption products. Closed-system degassing leads to an overpressure in the rising slug, which helps lift magma in the conduit, pressurising also the shallow system.</p><p>The gas plume produced by the 28 August 2019 eruption was observed approximately 2 hours after eruption by the orbiting TROPOMI imaging spectrometer aboard Sentinel-5P. Using the Plume Trajectory modelling approach, we have reconstructed a time series of SO<sub>2</sub> flux associated with the explosion.  This reveals no clear precursor in SO<sub>2</sub> emissions, but our temporal resolution is limited to 20-30 minutes. A total SO<sub>2</sub> mass of 360 tonnes was quantified.</p><p>We can use this SO<sub>2</sub> mass together with previously measured gas compositions of explosive gas emissions to quantify the total mass of gas at explosion and an estimate of the magma mass required to produce this SO<sub>2</sub> mass. Together, these provide the initial conditions required to apply a magma ascent model in which we calculate the overpressure of the slug during its ascent. This provides a basis for determining the shallow deformation produced by both the increase in magma level and over-pressurised gas slug, and this may be helpful in constraining the timescales of precursory deformation.</p><p> </p><p> </p>

A New Image Encryption Scheme Using Dual Chaotic Map Synchronization

2020 ◽  
Vol 18 (1) ◽  
Keyword(s):  
Image Encryption ◽  
Chaotic Systems ◽  
Initial Conditions ◽  
Chaotic Map ◽  
Security Applications ◽  
The Common ◽  
And Diffusion ◽  
Confusion And Diffusion ◽  
Sensitivity To Initial Conditions ◽  
Diffusion Properties

Chaotic systems behavior attracts many researchers in the field of image encryption. The major advantage of using chaos as the basis for developing a crypto-system is due to its sensitivity to initial conditions and parameter tunning as well as the random-like behavior which resembles the main ingredients of a good cipher namely the confusion and diffusion properties. In this article, we present a new scheme based on the synchronization of dual chaotic systems namely Lorenz and Chen chaotic systems and prove that those chaotic maps can be completely synchronized with other under suitable conditions and specific parameters that make a new addition to the chaotic based encryption systems. This addition provides a master-slave configuration that is utilized to construct the proposed dual synchronized chaos-based cipher scheme. The common security analyses are performed to validate the effectiveness of the proposed scheme. Based on all experiments and analyses, we can conclude that this scheme is secure, efficient, robust, reliable, and can be directly applied successfully for many practical security applications in insecure network channels such as the Internet

PARAMETER IDENTIFICATION FOR ELECTROCHEMICAL MODELS OF LITHIUM ION BATTERIES USING SENSITIVITY ANALYSIS

2021 ◽  
pp. 1-33
Author(s):  
Chitra Dangwal ◽  
Marcello Canova
Keyword(s):  
Parameter Identification ◽  
Large Scale ◽  
Initial Conditions ◽  
Lithium Ion ◽  
Optimization Methods ◽  
Particle Model ◽  
Aerospace Applications ◽  
Novel Approach ◽  
Consistent Solution ◽  
The Common

Abstract Predicting the chemical and physical processes occurring in Lithium-ion cells with high-fidelity electrochemical models is today a critical requirement to accelerate the design and optimization of battery packs for automotive and aerospace applications. One of the common issues associated with electrochemical models is the complexity of parameter identification, particularly when relying only on experimental data obtained via non-invasive techniques. This paper presents a novel approach to improve the common methods of parameter calibration that consists of matching the predicted terminal voltage to test data via optimization methods. The study is conducted for an NMC-graphite cell, modeled using a reduced order Extended Single Particle Model (ESPM). The proposed approach relies on using a large-scale Particle Swarm Optimization (PSO), modified by including a term that accounts for the parameter sensitivity information, such that the rate of convergence and robustness of the algorithm to obtain a consistent solution in the presence of uncertainties in the initial conditions are significantly improved.

scholarly journals Common envelope episodes that lead to double neutron star formation

2020 ◽  
Vol 37 ◽  
Author(s):  
Alejandro Vigna-Gómez ◽  
Morgan MacLeod ◽  
Coenraad J. Neijssel ◽  
Floor S. Broekgaarden ◽  
Stephen Justham ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Large Fraction ◽  
Computational Modelling ◽  
Evolutionary Stage ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Common Envelope ◽  
The Common ◽  
The Moment

Abstract Close double neutron stars (DNSs) have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational wave sources. They are believed to have experienced at least one common envelope episode (CEE) during their evolution prior to DNS formation. In the last decades, there have been numerous efforts to understand the details of the common envelope (CE) phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche lobe overflow (RLOF) leading to these CEEs as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the CE phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the RLOF: giant donors with fully convective envelopes, cool donors with partially convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of RLOF. This makes the study and understanding of eccentric mass-transferring systems relevant for DNS populations.

Accretion Processes

2018 ◽  
Author(s):  
Alessandro Morbidelli
Keyword(s):  
Solar System ◽  
Total Mass ◽  
Extrasolar Planets ◽  
Initial Conditions ◽  
Oort Cloud ◽  
Planetary Science ◽  
Solid Particles ◽  
Giant Planets ◽  
Irregular Satellites ◽  
Accretion Process

In planetary science, accretion is the process in which solids agglomerate to form larger and larger objects, and eventually planets are produced. The initial conditions are a disc of gas and microscopic solid particles, with a total mass of about 1% of the gas mass. These discs are routinely detected around young stars and are now imaged with the new generation of instruments. Accretion has to be effective and fast. Effective, because the original total mass in solids in the solar protoplanetary disk was probably of the order of ~300 Earth masses, and the mass incorporated into the planets is ~100 Earth masses. Fast, because the cores of the giant planets had to grow to tens of Earth masses to capture massive doses of hydrogen and helium from the disc before the dispersal of the latter, in a few millions of years. The surveys for extrasolar planets have shown that most stars have planets around them. Accretion is therefore not an oddity of the solar system. However, the final planetary systems are very different from each other, and typically very different from the solar system. Observations have shown that more than 50% of the stars have planets that don’t have analogues in the solar system. Therefore the solar system is not the typical specimen. Models of planet accretion have to explain not only how planets form, but also why the outcomes of the accretion history can be so diverse. There is probably not one accretion process but several, depending on the scale at which accretion operates. A first process is the sticking of microscopic dust into larger grains and pebbles. A second process is the formation of an intermediate class of objects called planetesimals. There are still planetesimals left in the solar system. They are the asteroids orbiting between the orbits of Mars and Jupiter, the trans-Neptunian objects in the distant system, and other objects trapped along the orbits of the planets (Trojans) or around the giant planets themselves (irregular satellites). The Oort cloud, source of the long period comets, is also made of planetesimals ejected from the region of formation of the giant planets. A third accretion process has to lead from planetesimals to planets. Actually, several processes can be involved in this step, from collisional coagulation among planetesimals to the accretion of small particles under the effect of gas drag, to giant impacts between protoplanets. Adopting a historical perspective of all these processes provides details of the classic processes investigated in the past decades to those unveiled in the last years. The quest for planet formation is ongoing. Open issues remain, and exciting future developments are expected.

scholarly journals On unbalanced data and common shock models in stochastic loss reserving

2020 ◽  
pp. 1-31
Author(s):  
Benjamin Avanzi ◽  
Greg Taylor ◽  
Phuong Anh Vu ◽  
Bernard Wong
Keyword(s):  
Unbalanced Data ◽  
Correlation Matrices ◽  
Structural Dependence ◽  
Common Shocks ◽  
Common Shock ◽  
Shock Models ◽  
Loss Reserving ◽  
The Common ◽  
Dependence Modelling ◽  
Modelling Approach

Abstract Introducing common shocks is a popular dependence modelling approach, with some recent applications in loss reserving. The main advantage of this approach is the ability to capture structural dependence coming from known relationships. In addition, it helps with the parsimonious construction of correlation matrices of large dimensions. However, complications arise in the presence of “unbalanced data”, that is, when (expected) magnitude of observations over a single triangle, or between triangles, can vary substantially. Specifically, if a single common shock is applied to all of these cells, it can contribute insignificantly to the larger values and/or swamp the smaller ones, unless careful adjustments are made. This problem is further complicated in applications involving negative claim amounts. In this paper, we address this problem in the loss reserving context using a common shock Tweedie approach for unbalanced data. We show that the solution not only provides a much better balance of the common shock proportions relative to the unbalanced data, but it is also parsimonious. Finally, the common shock Tweedie model also provides distributional tractability.

scholarly journals Universal algebraic convergence in time of pulled fronts: the common mechanism for difference-differential and partial differential equations

2002 ◽  
Vol 13 (1) ◽  
pp. 53-66 ◽  
Author(s):  
UTE EBERT ◽  
WIM VAN SAARLOOS ◽  
BERT PELETIER
Keyword(s):  
Differential Equation ◽  
Nonlinear Diffusion ◽  
Initial Conditions ◽  
Asymptotic Expression ◽  
Nonlinear Diffusion Equation ◽  
Common Mechanism ◽  
Propagation Mechanism ◽  
The Common ◽  
Algebraic Convergence ◽  
The Difference

We analyze the front structures evolving under the difference-differential equation ∂tCj = −Cj+C2j−1 from initial conditions 0 [les ] Cj(0) [les ] 1 such that Cj(0) → 1 as j → ∞ suffciently fast. We show that the velocity v(t) of the front converges to a constant value v* according to v(t) = v*−3/(2λ*t)+(3√π/2) Dλ*/(λ*2Dt)3/2+[Oscr ](1/t2). Here v*, λ* and D are determined by the properties of the equation linearized around Cj = 1. The same asymptotic expression is valid for fronts in the nonlinear diffusion equation, where the values of the parameters λ*, v* and D are specific to the equation. The identity of methods and results for both equations is due to a common propagation mechanism of these so-called pulled fronts. This gives reasons to believe that this universal algebraic convergence actually occurs in an even larger class of equations.

Dynamics of four coupled plasma waves to second order

1977 ◽  
Vol 18 (3) ◽  
pp. 525-536 ◽  
Author(s):  
Dolores Walters ◽  
George J. Lewak
Keyword(s):  
Initial Conditions ◽  
Plasma Waves ◽  
Negative Energy ◽  
Second Order ◽  
The Other ◽  
Coupling Constraints ◽  
The Common

General equations are derived for the interaction of four waves to second order (i.e. two triplets with two waves common to both). The solutions are analysed under various initial conditions and it is shown that the weaker triplet (as measured by the coupling constraints) is stabilized by the stronger one against explosive instabilities, whereas the converse does not happen. It is further found that under certain circumstances one of the common waves may act as a ‘catalyst’, remaining fixed in amplitude, while the other waves oscillate or even grow exponentially. This work extends the treatment of Karplyuk, Oraevskii & Pavlenko to include the possibility of negative energy waves.

Parking Control of Mixed Conventional/Braking Actuation Mobile Robots Using Fuzzy Logic Control

2016 ◽  
Author(s):  
Walelign M. Nikshi ◽  
Mark D. Bedillion ◽  
Randy C. Hoover
Keyword(s):  
Fuzzy Logic ◽  
Mobile Robot ◽  
Mobile Robots ◽  
Fuzzy Logic Controller ◽  
Initial Conditions ◽  
Robot System ◽  
Logic Control ◽  
The Common ◽  
Actuation Systems ◽  
Robot Platform

In this paper a new mobile robot system, the mixed conventional/braking actuation mobile robot (MAMR), is introduced. Various actuation systems exist for mobile robots such as differential drive with motor-driven wheels, legged mechanisms, and others. The common characteristics of all those actuation systems is the use of conventional motors to move each degree of freedom. Robots with such actuation systems are generally complex, heavy, and expensive. This paper uses brakes in combination with conventional actuators to tackle those drawbacks. In this study, some of the conventional actuators are replaced by brakes resulting a new mobile robot platform. Two states of brakes (i.e. ON/OFF) which are obtained by assuming Coulomb friction at the brake are considered. This paper discusses the dynamics and parking control of such a robot using a fuzzy logic controller. Several Matlab/Simulink simulations with different initial conditions are done to show the effectiveness of the proposed controller.

Free Fall of a Sphere in a Partially Lubricated Cylinder

1991 ◽  
Vol 58 (3) ◽  
pp. 812-819
Author(s):  
Roger F. Gans
Keyword(s):  
Contact Force ◽  
Closed System ◽  
Experimental Verification ◽  
Asymptotic Expansions ◽  
Total Mass ◽  
Free Fall ◽  
Matched Asymptotic Expansions ◽  
Biological Applications ◽  
Slider Bearing ◽  
Acceleration Of Gravity

The entrainment of lubricant at the entrance of a lubrication zone, such as that of a partially starved slider bearing, is analyzed in a closed system using the method of matched asymptotic expansions. A sphere falling together with a small lens of lubricant in a closely fitting tube is shown to fall under gravity at a speed V=(Mg−Fc)√[(RC−RS)/RC]/(16π2μRC), where M denotes the total mass of the system, sphere plus lubricant, g the acceleration of gravity, Fc the differential contact force, μ the viscosity of the lubricant, and RC and RS the radii of the tube and the sphere, respectively. Potential biological applications and experimental verification are discussed.

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