Search results for "Dynamic models"

A Simple Mechanical Model for Simulating Cross-Country Skiing Propulsive Force

2015

In this paper, a three-dimensional multibody dynamic model of a cross-country skier is developed and presented where a single propulsion phase is modeled to obtain the kinetic parameters involved in the movement. A professional Olympic-level skier performed the skating technique without poles in a ski tunnel under controlled conditions and on an incline plane. Then, with the use of a force acquisition system attached to the ski bindings and a motion capture system set on site, the leg resultant forces and the movement of specific points of the skier’s lower body were acquired. The data obtained from the motion capture system was used as the prescribed kinematic input data in the multibody m…

A probabilistic estimation and prediction technique for dynamic continuous social science models: The evolution of the attitude of the Basque Country…

2015

In this paper, a computational technique to deal with uncertainty in dynamic continuous models in Social Sciences is presented.Considering data from surveys,the method consists of determining the probability distribution of the survey output and this allows to sample data and fit the model to the sampled data using a goodness-of-fit criterion based the χ2-test. Taking the fitted parameters that were not rejected by the χ2-test, substituting them into the model and computing their outputs, 95% confidence intervals in each time instant capturing the uncertainty of the survey data (probabilistic estimation) is built. Using the same set of obtained model parameters, a prediction over …

Epidemic spreading and aging in temporal networks with memory

2018

Time-varying network topologies can deeply influence dynamical processes mediated by them. Memory effects in the pattern of interactions among individuals are also known to affect how diffusive and spreading phenomena take place. In this paper we analyze the combined effect of these two ingredients on epidemic dynamics on networks. We study the susceptible-infected-susceptible (SIS) and the susceptible-infected-removed (SIR) models on the recently introduced activity-driven networks with memory. By means of an activity-based mean-field approach we derive, in the long time limit, analytical predictions for the epidemic threshold as a function of the parameters describing the distribution of …

Minimal Dynamic Equilibria

2018

We define dynamic models as multiperiod models with no static representations and demonstrate that current prevalent asset pricing empirical implementations are inconsistent with dynamic equilibria. Specifically, empirical implementations are misspecified with respect to three essential asset pricing questions (TEQ): dependency on higher moments, complexity of risk premia, and mean-variance efficiency of the “market portfolio” (ability to proxy pricing kernels/SDFs). While we already know that “Merton” models, and their derivatives, differ from static models in all TEQ, we show that this is the case even the “minimal” dynamic equilibria.

Exploring the applicability of dissipative fluid dynamics to small systems by comparison to the Boltzmann equation

2018

[Background] Experimental data from heavy-ion experiments at RHIC-BNL and LHC-CERN are quantitatively described using relativistic fluid dynamics. Even p+A and p+p collisions show signs of collective behavior describable in the same manner. Nevertheless, small system sizes and large gradients strain the limits of applicability of fluid-dynamical methods. [Purpose] The range of applicability of fluid dynamics for the description of the collective behavior, and in particular of the elliptic flow, of small systems needs to be explored. [Method] Results of relativistic fluid-dynamical simulations are compared with solutions of the Boltzmann equation in a longitudinally boost-invariant picture. …

Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at √sNN = 2.76 TeV

2018

The correlations between event-by-event fluctuations of anisotropic flow harmonic amplitudes have been measured in Pb-Pb collisions at √ s NN = 2.76 TeV with the ALICE detector at the Large Hadron Collider. The results are reported in terms of multiparticle correlation observables dubbed symmetric cumulants. These observables are robust against biases originating from nonflow effects. The centrality dependence of correlations between the higher order harmonics (the quadrangular v 4 and pentagonal v 5 flow) and the lower order harmonics (the elliptic v 2 and triangular v 3 flow) is presented. The transverse momentum dependences of correlations between v 3 and v 2 and between v 4 and v 2 are …

Prevention of marine pollution from oil spill: The activities of MAPRES project

2008

Predictions for multiplicities and flow harmonics in 5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider

2018

We present the next-to-leading-order event-by-event EKRT model predictions for the centrality dependence of the charged hadron multiplicity in the pseudorapidity interval $|\eta|\le 0.5$, and for the centrality dependence of the charged hadron flow harmonics $v_n\{2\}$ obtained from 2-particle cumulants, in $\sqrt{s_{NN}}=5.44$ TeV Xe+Xe collisions at the CERN Large Hadron Collider. Our prediction for the 0-5 \% central charged multiplicity is $dN_{\rm ch}/d\eta =1218\pm 46$. We also predict $v_n\{2\}$ in Xe+Xe collisions to increase more slowly from central towards peripheral collisions than those in a Pb+Pb system. We find that at $10 \dots 50$\% centralities $v_2\{2\}$ is smaller and $v_…

Exploiting Valve Timing for Pneumatic Energy Savings

2018

This research paper aims at addressing solutions that reduce air consumption in generic pneumatic systems used for pick-and-place operations. The investigation considers different system architectures both with a single control valve and two control valves arranged according to an independent metering configuration. Suitable control strategies are then proposed exploiting multiple timings to shut off the non-proportional switching valve(s). The resulting scenarios are experimentally evaluated on a dedicated test-bed. The main conclusion is that reduction of air consumption up to 73% is possible in comparison to the state-of-the-art layout for the reference application. Numerical simulations…

Predicting human performance in interactive tasks by using dynamic models

2017

The selection of an appropriate sequence of activities is an essential task to keep student motivation and foster engagement. Usually, decisions in this respect are made by taking into account the difficulty of the activities, in relation to the student's level of competence. In this paper, we present a dynamic model that aims to predict the average performance of a group of students at solving a given series of maths problems. The system takes into account both student- and task-related features. This model was built and validated by using the data gathered in an experimental session that involved 64 participants solving a sequence of 26 arithmetic problems. The data collected from the fir…