A magneto rheological hybrid damper for railway vehicles suspensions

High speed railway vehicles features a specific lateral oscillation resulting from the coupled lateral displacement and yaw of the wheelset which leads to a sinusoid movement of the wheelset along the track, transferred to the entire vehicle. The amplitude of this oscillation is strongly dependant on vehicle’s velocity. Over a certain value, namely the critical speed, the instability phenomenon so-called hunting occurs. To raise the vehicle’s critical speed different designs of the suspension all leading to a much stiffer vehicle can be envisaged. Different simulations prove that a stiffer central suspension will decrease the passenger’s comfort in terms of lateral accelerations of the carboy. The authors propose a semi-active magneto rheological suspension to improve the vehicle’s comfort at high speeds. The suspension has as executive elements hybrid magneto rheological dampers operating under sequential control strategy type balance logic. Using an original mathematical model for the lateral dynamics of the vehicle the responses of the system with passive and semi-active suspensions are simulated. It is shown that the semi-active suspension can improve the vehicle performances

Study of the railway vehicle suspension using the multibody method

The article presents a mathematical model for the study of a passenger coach hunting motion using the multibody approach. The model comprises the lateral displacement, rolling and yawing motions for the main constitutive elements: axles, bogies and case. The equation system is written applying energetic methods. The forced vibrations determined by the irregular profile of the tracks are considered. The wheel – rail contact forces are expressed using the creepage coefficients established according to Kalker's linear theory. The equations system is solved through numeric methods using specialized calculus programs. The response of the system – passenger coach on a tangent track, the critical speed and the influence of the constructive characteristics of the coach on its performances are determined

Zeus

Treball desenvolupat dins el marc del programa 'European Project Semester'.Nowadays, being a smart city is becoming more important. It is because of increasing energy use and the costs that come with it, that people all over the world are looking for better methods to decrease the environmental effects and costs. Therefore, the purpose of this research is to find out if there is a better way to use the streetlights in Vilanova i la Geltrú in order to go forward in the direction of being a smart city. Vilanova i la Geltrú currently has 10.800 Streetlights, and the energy consumption for these street lights cost a huge amount of money each year. This number can be decreased by finding new ways. This will be done, by further developing a street light called the ‘Urban Node’. This further development will be based on a previous research done. This Urban Node will be a replacement of the current street light. It includes components like led lights, solar panel and a wind turbine. It generates energy by using wind turbines and a solar panel instead of the current regular street light. In this research a certain methodology has been used, which includes expert interviews, an observation and desk research. As a result of using these methods, there has been made a simulation of a renewed streetlight system mostly revolving around the new product adding to the current system, which is the Urban Node. Concluding the results it has been found that implementing the Urban Node is more cost and energy efficient than the current street light system that has been used within Vilanova i la Geltrù. Furthermore, in this report there will be explained what the Urban Node exactly is, how it is structured, where it should be implemented, how it should be implemented and how it is more cost and energy efficient than the current system

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements