An exact fluid model for relativistic electron beams: The many moments case

An interesting and satisfactory fluid model has been proposed in literature for the the description of relativistic electron beams. It was obtained with 14 independent variables by imposing the entropy principle and the relativity principle. Here the case is considered with an arbitrary number of independent variables, still satisfying the above mentioned two principles; these lead to conditions whose general solution is here found. We think that the results satisfy also a certain ordering with respect to a smallness parameter $\epsilon$ measuring the dispersion of the velocity about the mean; this ordering generalizes that appearing in literature for the 14 moments case

A Bird’s-Eye View of the Loan Shark Problem From the Offices of the Legal Aid Society in Atlanta, Georgia

The aim of this thesis is to create a computer program that simulates the motionof cells in a developing embryo. The resulting simulator is to be used by in the CellLineage project (Robert Forchheimer et al.) as an input to their genetic model, themeta-Boolean model [18]. This genetic model is not the focus of this work. Sincethe simulated system is highly complex, with fluids and deforming soft bodies, itis unfeasible to simulate the system in a physically realistic manner while keepingexecution time to reasonable values. Therefore some physical realism is sacrificedin favor of simulation stability and execution speed.The resulting simulator, Cell-Lab, uses Position Based Dynamics (PBD) [17] toimplement a number of different models for the cell’s mechanical properties. PBDis well suited for this purpose since it, while not taking excessively long time toexecute, guarantees an unconditionally stable simulation. The simulator includesa hard eggshell surrounding the cells. Cells can be split during the simulation,emulating mitosis. There is also the possibility to simulate cell adhesion usinga cadherin like mechanism. To control when and how cells are split and fetchinformation about the current state of the simulation there is an interface to beused by external applications. The meta-Boolean model can be implemented insuch an applicatio

Ultrarelativistic limit of a Rarefied Gas with Internal Structure

The aim of this letter is to check the ultra-relativistic limit of a recent model proposed by Pennisi and Ruggeri [Ann. Phys. 377, 414 (2017)] for a relativistic gas with internal structure. Considering an Eulerian fluid we prove that there exists a critical value of the degree of freedom such that for smaller values of this quantity the ultra relativistic limit of the energy of a gas with structure is the same as the Synge energy for monatomic gases, while for larger degrees of freedom the energy increases with the degree of freedom itself. The limiting equations are accompanied with the explicit expression of the characteristic velocities of the hyperbolic system.Comment: 4 pages, 2 figure

Calculations for Extended Thermodynamics of dense gases up to whatever order and with all the symmetries

The 14 moments model for dense gases, introduced in the last years by Arima, Taniguchi Ruggeri, Sugiyama, is here considered. They have found the closure of the balance equations up to second order with respect to equilibrium; here the closure is found up to whatever order with respect to equilibrium, but for a more constrained system where more symmetry conditions are imposed and this in agreement with the suggestion of the kinetic theory. The results, when restricted at second order with respect to equilibrium, are the same of the previously cited model but under the further restriction of full symmetries.Comment: arXiv admin note: substantial text overlap with arXiv:1410.405

The Macroscopic Approach to Extended Thermodynamics with 14 Moments, Up to Whatever Order

Extended Thermodynamics is the natural framework in which to study the physics of fluids, because it leads to symmetric hyperbolic systems of field laws, thus assuming important properties such as finite propagation speeds of shock waves and well posedness of the Cauchy problem. The closure of the system of balance equations is obtained by imposing the entropy principle and that of galilean relativity. If we take the components of the mean field as independent variables, these two principles are equivalent to some conditions on the entropy density and its flux. The method until now used to exploit these conditions, with the macroscopic approach, has not been used up to whatever order with respect to thermodynamical equilibrium. This is because it leads to several difficulties in calculations. Now these can be overcome by using a new method proposed recently by Pennisi and Ruggeri. Here we apply it to the 14 moments model. We will also show that the 13 moments case can be obtained from the present one by using the method of subsystems

Online real-time crowd behavior detection in video sequences

Automatically detecting events in crowded scenes is a challenging task in Computer Vision. A number of offline approaches have been proposed for solving the problem of crowd behavior detection, however the offline assumption limits their application in real-world video surveillance systems. In this paper, we propose an online and real-time method for detecting events in crowded video sequences. The proposed approach is based on the combination of visual feature extraction and image segmentation and it works without the need of a training phase. A quantitative experimental evaluation has been carried out on multiple publicly available video sequences, containing data from various crowd scenarios and different types of events, to demonstrate the effectiveness of the approach

An exact macroscopic extended model with many moments

Extended Thermodynamics is a very important theory: for example, it predicts hyperbolicity, finite speeds of propagation waves as well as continuous dependence on initial data. Therefore, it constitutes a significative improvement of ordinary thermodynamics. Here its methods are applied to the case of an arbitrary, but fixed, number of moments. The kinetic approach has already been developed in literature; then, the macroscopic approach is here considered and the constitutive functions appearing in the balance equations are determined up to whatever order with respect to thermodynamical equilibrium. The results of the kinetic approach are a particular case of the present ones