The GPS, the radar systems, or even satellite communications, all these applications, and devices have one thing in common, they work using frequency-encoded data.
In order to decode the valuable information, all these systems use special algorithms to accurately estimate the main frequency of the digital signals they work with.
Many have been the algorithms proposed throughout the second half of the 20th century to estimate in real-time the main frequency of a certain digital signal, however, only a bunch of them are simple enough in terms of numerical complexity to be fit for the embedded software of limited computational-capability devices (like the Raspberry Pi). …
Since the introduction of the first non-experimental digital fly-by-wire system in the F-8 Crusader, the exponential growth of the embedded control systems computing power has enabled the military aerospace industry to develop more efficient and agile aircraft.
Generally, modern fighters are designed to be naturally unstable for the sake of maneuverability and agility, requiring the use of Flight Control Laws (FCL) to artificially stabilize the aircraft dynamics and to provide diverse safety-critical flight envelope protection functions, along with automatic or semiautonomous flight modes.
To ensure the safe operation of the aircraft and the correct functioning of the FCL, a clearance assessment must be performed. …
It was a humid morning on February 25th of 2008 in the Andersen Air Force Base in Guam.
That day more than $1,400,000,000 were lost, two lives were saved, and an engineering work of art was scrapped, the B-2 stealth bomber “Spirit of Kansas” crashed and burst into flames seconds after the lift-off.
The first accident of a B-2 stealth bomber since it passed its testing period, 20 years ago, was caused by humidity that affected the aircraft’s air data system, providing erroneous lectures of airspeed and angle of attack to the Flight Control System.
The erroneous voting and consensus between the different Air Data System’s sensors feeding the “fly-by-wire” control system led to a catastrophic combination of large airspeed over-reading and angle of attack under-reading errors. …
The frequency-domain analysis allows extracting information that is not obvious by simply observing a signal in time.
Nowadays frequency-domain algorithms are the backbone of many lossy compression data methods like the JPEG for image files or the MP3 for music files.
Most of these algorithms are a derivation of the Continuous Fourier Transform (CFT), originally proposed in 1822 by Jean-Baptiste Joseph Fourier, the father of modern engineering.
The problem with CFT is that it can only be applied to analogical signals, and we all live in a digital/discrete world.
Today, countless industrial and technological applications have benefited from the latest advances in the field of Artificial Intelligence (AI).
From mobile applications, that put you in the shoes of Robert Downey Jr. in an Iron Man movie scene, to planes that take off and land autonomously using image recognition algorithms to detect the position of the runway.
However, in most practical applications, the neural networks have been previously trained off-line, and in the deployment and industrialization stage, their parameters, weights, and architecture are frozen.
In other words, these neural networks are static, and their ability to learn during their in-service life has been restricted. …
I want you to visualize this scene. Imagine you had to fill up your car while you are traveling at 300mph, and the pump is also moving, and also the hose is moving around the pump?
You can’t just roll down the window and grab the nozzle with your hand, you have to drive your car — a car which is more like a truck — and align the filler with the nozzle just so.
And now let’s add wind and turbulence to randomly perturb the motion of your car, the pump, and the hose of course.
Oh! And now let there be complete darkness, on a dark night with a new moon and rainy weather. …
I still nowadays enjoy reading and going through old photos of the experimental planes NASA developed in the good old days of the aviation pioneers, the old days of the X-Plane program.
NASA started the X-Plane program — the X is for eXperimental — in 1946, and has since developed 57 prototypes — although not all of them have flown (like the X-27 High-Performance Fighter).
The objective of this program was to test new technologies, usually keeping their development secret.
Sadly, despite a long history of incredible achievements, the X-Plane program has remained inactive since 2013, although it has never been canceled — its budget was allocated to other NASA’s research topics that required some investment. …
The race to achieve improvements in airliners’ energy efficiency seems to never end.
Currently, the improvements in aerodynamic efficiency and specific consumptions in the new generation of aircraft and engines do not exceed the 10% threshold compared to the previous generation.
These improvements have been achieved mainly thanks to the latest innovations in the following fields:
None of these technologies by itself provide a massive increase in aircraft energy efficiency, but when they are combined in the right way, voilà! …
In any personal learning process, there is a balance between the theoretical and the practical experience.
On some occasions, we may be tempted to underestimate the theoretical basis of the subject of interest and jump right into solving practical problems, thinking that if we can solve a certain problem in a practical exercise, we will know how to solve any type of problem.
When I was young, my father always told me that I had to learn first the theoretical basis and internalize the most abstract concepts, to then be able to extrapolate and generalize.
Of course, my father’s example may not be of any relevance to you, but there are other well-known smart guys who have the same opinion as my father. …
The Bell AH-1 has been in service with the United States Marine Corps for fifty-one years. During this period, the Marines have operated various variants of the Bell AH-1, from the single-engine AH-1G to the twin-engine AH-1Z.
Now, after 34 years, they have retired their last AH-1W, the last of those equipped with a two-bladed rotor, leaving only the AH-1Z with a four-bladed rotor in service.
The AH-1W made its first flight on November 16, 1983, and deliveries to the Marines began on March 27, 1986, with a total of 179 units delivered until 1999, having participated in numerous combat actions, since the invasion of Grenada to fight the Islamic State, through the liberation of Kuwait, and the conflict in the Balkans. …