Constraining Jupiter's internal flows using Juno magnetic and gravity measurements

Deciphering the flow below the cloud-level of Jupiter remains a critical milestone in understanding Jupiter's internal structure and dynamics. The expected high-precision Juno measurements of both the gravity field and the magnetic field might help to reach this goal. Here we propose a method that combines both fields to constrain the depth-dependent flow field inside Jupiter. This method is based on a mean-field electrodynamic balance that relates the flow field to the anomalous magnetic field, and geostrophic balance that relates the flow field to the anomalous gravity field. We find that the flow field has two distinct regions of influence: an upper region in which the flow affects mostly the gravity field and a lower region in which the flow affects mostly the magnetic field. An optimization procedure allows to reach a unified flow structure that is consistent with both the gravity and the magnetic fields

Critical rainfall thresholds for triggering shallow landslides in the Serchio River Valley (Tuscany, Italy)

Abstract. The Serchio River Valley, in north-western Tuscany, is a well-known tourism area between the Apuan Alps and the Apennines. This area is frequently hit by heavy rainfall, which often triggers shallow landslides, debris flows and debris torrents, sometimes causing damage and death. The assessment of the rainfall thresholds for the initiation of shallow landslides is very important in order to improve forecasting and to arrange efficient alarm systems. With the aim of defining the critical rainfall thresholds for the Middle Serchio River Valley, a detailed analysis of the main rainstorm events was carried out. The hourly rainfall recorded by three rain gauges in the 1935–2010 interval was analysed and compared with the occurrence of shallow landslides. The rainfall thresholds were defined in terms of mean intensity I, rainfall duration D, and normalized using the mean annual precipitation. Some attempts were also carried out to analyze the role of rainfall prior to the damaging events. Finally, the rainfall threshold curves obtained for the study area were compared with the local, regional and global curves proposed by various authors. The results of this analysis suggest that in the study area landslide activity initiation requires a higher amount of rainfall and greater intensity than elsewhere

Evaluation of subsidence induced by long-lasting buildings load using InSAR technique and geotechnical data: The case study of a Freight Terminal (Tuscany, Italy)

This paper shows the results of the comparison between Multi-temporal Synthetic Aperture Radar (MTInSAR) products derived from different sensors (C-band ERS 1/2, Envisat, Sentinel-1 and X-band COSMO-SkyMed) and geotechnical data to investigate the driving factors of subsidence which affect a freight terminal located along the a coastal plain of Tuscany (central Italy). MTInSAR data have been acquired in a very long period, between 1992 and 2018 and were analyzed in terms of subsidence rates and deformation time series at building scale. The obtained results show that the oldest buildings are still affected by a deformation rate close to −5 mm/yr, whereas recent buildings register rates around −40 mm/yr. Time series of deformation suggest that the deformation rates decrease over time following time-dependent trend that approximates the typical consolidation curve for compressible soils. The geotechnical and stratigraphical analysis of the subsurface data (boreholes, cone penetration tests and dilatometer tests) highlights the presence of a 15 m thick layer formed of clay characterized by poor geotechnical characteristics. The comparison among InSAR data, subsurface geological framework and geotechnical reconstruction suggests a possible evaluation of the timing of the primary and secondary consolidation processes

Adaptive Basketball Shooter - Final Project Report

The Friday Club is a joint venture between the Cal Poly Kinesiology Department and the San Luis Obispo Special Olympics that offers people with varying degrees of disability the opportunity to meet weekly and learn various sports and games. At Friday Club, athletes in wheelchairs with limited arm strength use devices built by Cal Poly mechanical engineering students in order to participate in various sports. Many devices are designed to attach to the Universal Play Frame (UPF), a wheel-chair attachment. The purpose of this project was to design and build a UPF device that will launch a basketball, so that an athlete can participate in a game of “Horse.” The project was worked on over the course of the 2013-2014 school year. To begin, the team developed a list of objectives for the device to meet and researched existing solutions for various facets of our design. The next step was to generate concepts of our device, and using Pugh matrices, proof of concept testing, and debate to narrow down to a single concept. Next, this concept was transformed into a fully-fledged design backed by engineering analysis. After design approval, all necessary parts and materials were ordered and a prototype was built over a 10 week period. The final prototype was tested with the Friday Club and displayed at the Senior Project Expo on May 31, 2014. The final device that our team designed is a slingshot that launches the ball by releasing stretched elastic bands. Our design attaches to the UPF at two points, and can be aimed to shoot a basket from anywhere between 5 and 15 feet away. The athlete has the ability to control the direction, power, and release of each shot. The device can be set up in under five minutes by a single person and takes only 30 seconds to reset between shots. Of all customer requirements that the device was to meet, it only failed to meet one of them. The first was that it should be able to shoot a three-pointer. Unfortunately, our device either did not have strong enough elastic, or did not have enough space to pull back the ball and carriage sufficiently. Therefore, our device can shoot a basket from a maximum of only 15 feet away, or a free throw. Other future recommendations are to strengthen some parts that take high impacts and to reduce the weight of some unnecessarily bulky parts. Our budget for this project was $1,500 but over the course of this project our team spent a little over$1,750. After analyzing our spending, we found that over $300 was spent because of manufacturing mistakes and mid-construction design changes. If we were to build another device with the exact same design as our final prototype, and with no mistakes, the device would cost about$1,400. In this report, our team’s entire design process is cataloged in detail. Also enclosed are detailed part drawings for each manufactured part of our final device, as well as a safety and operation manual

Constraining Jupiter's internal flows using Juno magnetic and gravity measurements

Deciphering the flow below the cloud-level of Jupiter remains a critical milestone in understanding Jupiter's internal structure and dynamics. The expected high-precision Juno measurements of both the gravity field and the magnetic field might help to reach this goal. Here we propose a method that combines both fields to constrain the depth-dependent flow field inside Jupiter. This method is based on a mean-field electrodynamic balance that relates the flow field to the anomalous magnetic field, and geostrophic balance that relates the flow field to the anomalous gravity field. We find that the flow field has two distinct regions of influence: an upper region in which the flow affects mostly the gravity field and a lower region in which the flow affects mostly the magnetic field. An optimization procedure allows to reach a unified flow structure that is consistent with both the gravity and the magnetic fields

Jupiter's envelope is not homogeneous

Stars and planetary system

Jupiter's interior from Juno: Equation-of-state uncertainties and dilute core extent

The Juno mission has provided measurements of Jupiter s gravity field with an outstanding level of accuracy, leading to better constraints on the interior of the planet. Improving our knowledge of the internal structure of Jupiter is key to understanding its formation and evolution but is also important in the framework of exoplanet exploration. In this study, we investigated the differences between the state-of-the-art equations of state and their impact on the properties of interior models. Accounting for uncertainty on the hydrogen and helium equation of state, we assessed the span of the interior features of Jupiter. We carried out an extensive exploration of the parameter space and studied a wide range of interior models using Markov chain Monte Carlo (MCMC) simulations. To consider the uncertainty on the equation of state, we allowed for modifications of the equation of state in our calculations. Our models harbour a dilute core and indicate that Jupiter s internal entropy is higher than what is usually assumed from the Galileo probe measurements. We obtain solutions with extended dilute cores, but contrary to other recent interior models of Jupiter, we also obtain models with small dilute cores. The dilute cores in such solutions extend to 20% of Jupiter s mass, leading to better agreement with formation evolution models. We conclude that the equations of state used in Jupiter models have a crucial effect on the inferred structure and composition. Further explorations of the behaviour of hydrogen helium mixtures at the pressure and temperature conditions in Jupiter will help to constrain the interior of the planet, and therefore its origin

Flame front propagation IV: Random Noise and Pole-Dynamics in Unstable Front Propagation II

The current paper is a corrected version of our previous paper arXiv:adap-org/9608001. Similarly to previous version we investigate the problem of flame propagation. This problem is studied as an example of unstable fronts that wrinkle on many scales. The analytic tool of pole expansion in the complex plane is employed to address the interaction of the unstable growth process with random initial conditions and perturbations. We argue that the effect of random noise is immense and that it can never be neglected in sufficiently large systems. We present simulations that lead to scaling laws for the velocity and acceleration of the front as a function of the system size and the level of noise, and analytic arguments that explain these results in terms of the noisy pole dynamics.This version corrects some very critical errors made in arXiv:adap-org/9608001 and makes more detailed description of excess number of poles in system, number of poles that appear in the system in unit of time, life time of pole. It allows us to understand more correctly dependence of the system parameters on noise than in arXiv:adap-org/9608001Comment: 23 pages, 4 figures,revised, version accepted for publication in journal "Combustion, Explosion and Shock Waves". arXiv admin note: substantial text overlap with arXiv:nlin/0302021, arXiv:adap-org/9608001, arXiv:nlin/030201

The effect of differential rotation on Jupiter's low-degree even gravity moments

The close-by orbits of the ongoing Juno mission allow measuring with unprecedented accuracy Jupiter's low-degree even gravity moments J(2), J(4), J(6), and J(8). These can be used to better determine Jupiter's internal density profile and constrain its core mass. Yet the largest unknown on these gravity moments comes from the effect of differential rotation, which gives a degree of freedom unaccounted for by internal structure models. Here considering a wide range of possible internal flow structures and dynamical considerations, we provide upper bounds to the effect of dynamics (differential rotation) on the low-degree gravity moments. In light of the recent Juno gravity measurements and their small uncertainties, this allows differentiating between the various models suggested for Jupiter's internal structure.Israeli Ministry of Science; Minerva foundation; Federal German Ministry of Education and Research; Helen Kimmel Center for Planetary Science at the Weizmann Institute of Science; CNES; BSF; NSF; Juno project6 month embargo; Published Online: 19 June 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Flame front propagation V: Stability Analysis of Flame Fronts: Dynamical Systems Approach in the Complex Plane

We consider flame front propagation in channel geometries. The steady state solution in this problem is space dependent, and therefore the linear stability analysis is described by a partial integro-differential equation with a space dependent coefficient. Accordingly it involves complicated eigenfunctions. We show that the analysis can be performed to required detail using a finite order dynamical system in terms of the dynamics of singularities in the complex plane, yielding detailed understanding of the physics of the eigenfunctions and eigenvalues.Comment: 17 pages 7 figure