If you have a bike, most surely you will own a helmet too. If you fall off the bike your helmet might avoid some nasty head injuries, right? That looks pretty obvious… except that it isn’t. Lets start with a little bit of skepticism, and as straightforward as it seems, we would like some proof […]
Of all the seven wonders of ancient times, only the pyramids of Egypt remain on their feet. The technical means Egyptians had that many years ago for building these huge structures were extremely limited, and that is the main reason for them being so fascinating: they could build them despite the huge technical difficulties they […]
Bicycles are usually regarded as the most sustainable mean of transport for urban environments. Now, when talking about sustainability, there are usually two different discussions: on the one hand, there is energy sustainability, as the fossil fuels won’t last forever and their secondary products are quite unhealthy. Bikes, being powered by people, fully comply with […]
Classic rail vehicles have rigid wheelsets: both wheels are interlocked and have the same degrees of freedom (DoF), so they share all their displacements. They also have positive conicity, this is, the wheel surface on the contact patch is conical and, if we extend these ideal cones, their base would meet at the centre of […]
The locomotion of every moving system, alive or manufactured, is produced by the interaction between some movable components or appendages and the surrounding environment. This applies for every kind of surroundings: land, water or air. For water and air, Navier-Stokes equations allow predicting the interaction with the fluid with very high precision. In the case […]
Maples rely on wind, upward currents, and gusts to spread their seeds over long distances that can reach several kilometers. Maple seeds are able to autorotate because their center of gravity, determined by the position of the nut, is located at the base of the wing-shaped seed. It has been observed that, despite their small […]
Unlike road vehicles, all rail vehicles run through exactly the same piece of track and they cannot drift away to avoid a bad quality rail. Moreover, the contact patch between wheel and rail is a steel-to-steel contact with a small area and huge loads, so the stress the material is subject to is extremely high […]
If you have ever faced that thankless task of cleaning fish, for sure you will have realized, at least envisaged, the complex architecture of the fish’s natural armour. Fish scales play the role of a skeleton which provides both protection and flexibility at the same time. It goes without saying that this fact has not […]
Humans can build and use the most sophisticated tools. One of the reasons is the configuration of our hands, which enable us to hold items in a very convenient way. But further than that, we can actually grab items because of the friction coefficient that exists between the skin of our hands and the surface […]
High speed trains are the best example of vehicles that, although operating at somehow extreme conditions, are very comfortable. And by comfort I mean that the vibration level that passengers feel is relatively low. The components that allow this level of comfort are the pneumatic springs, torus-shaped rubber elements filled with pressured air. Their behaviour […]