John Napier was a Scottish physicist, mathematician, and astronomer who usually gets the credit for inventing logarithms. But his contributions to simplifying mathematics and building shorthand solutions didn’t end there. In the course of performing the many calculations he needed to practice these subjects in the 1500s, Napier invented a kind of computing mechanism for multiplication. It’s a physical manifestation of an old system known as lattice multiplication or gelosia.
Lattice multiplication makes use of the multiplication table in order to multiply huge numbers together quickly and easily. It is thought to have originated in India and moved west into Europe. When the lattice method reached Italy, the Italians named it gelosia after the trellised window covering it resembled, which was commonly used to keep prying eyes away from one’s possessions and wife.
Continue reading “Bone Up on Your Multiplication Skills”
What if you could give yourself a standard eye exam at home? That’s the idea behind [Joel, Margot, and Yuchen]’s final project for [Bruce Land]’s ECE 4760—simulating the standard Snellen eye chart that tests visual acuity from an actual or simulated distance of 20 feet.
This test is a bit different, though. Letters are presented one by one on a TFT display, and the user must identify each letter by speaking into a microphone. As long as the user guesses correctly, the system shows smaller and smaller letters until the size equivalent to the 20/20 line of the Snellen chart is reached.
Since the project relies on speech recognition, the group had to consider things like background noise and the differences in human voices. They use a bandpass filter to screen out frequencies that fall outside the human vocal range. In order to determine the letter spoken, the PIC32 collects the first 256 and last 256 samples, stores them in two arrays, and performs FFT on the first set. The second set of samples undergoe Mel transformation, which helps the PIC assess the sample logarithmically. Finally, the system determines whether it should show a new letter at the same size, a new letter at a smaller size, or end the exam.
While this is not meant to replace eye exams done by certified professionals, it is an interesting project that is true to the principles of the Snellen eye chart. The only thing that might make this better is an e-ink display to make the letters crisp. We’d like to see Snellen’s tumbling E chart implemented as well for children who don’t yet know the alphabet, although that would probably require a vastly different input method. Be sure to check out the demonstration video after the break.
Don’t know who [Bruce Land] is? Of course he’s an esteemed Senior Lecturer at Cornell University. But he’s also extremely active on Hackaday.io, has many great embedded engineering lectures you can watch free-of-charge, and every year we look forward to seeing the projects — like this one — dreamed and realized by his students. Do you have final projects of your own to show off? Don’t be shy about sending in a tip!
Continue reading “Students Set Sights on DIY Eye Exams”
As you know, winter is coming. For a lot of people this means that Seasonal Affective Disorder is beginning to set in. [Luke]’s mom already has a light therapy box. It’s one of those commercially available ones that uses fluorescent bulbs and leaves a lot to be desired in the full-spectrum light simulation department. [Luke] jumped on the opportunity to design a better one.
The standard of quality for light therapy units is a rating of 10,000 lux. While lux definitely matters, the rating is a misleading selling point when given on its own. One of the other important factors in mimicking the sun is the Color Rendering Index (CRI). CRI is basically a rating of the bulb’s ability to imitate the color reproduction of natural daylight. The ratings run from 0 to 100 but in reality, the highest-rated bulbs of any kind top out around 98.
For all the fluorescent bulb-bearing light therapy units out there, those bulbs have pretty low CRI ratings. [Luke]’s project page provides emission spectra graphs for a number of bulb types, and we can see how his choice of ceramic metal halide bulbs stacks up against fluorescent, incandescent, and LED bulbs. One of the few downsides to this type of bulb is that they have long startup times.
He ended up making two light therapy lamps, one of them directional and the other omni-directional. They both use ballast-controlled ceramic metal halide bulbs. The ballasts are necessary to provide the high starting voltage that these bulbs require. The omni-directional light is built into a large hurricane candle holder. A lamp holder is fixed into the base and wired to an external ballast box. The directional lamp is a self-contained unit, and [Luke] is happiest with this one. It’s flat and rugged so it can be placed on top of a bookcase and the light bounced off of the ceiling for pleasant, indirect coverage.
We’ve seen a couple of alarm-clock wakeup light builds here, and we’re thinking this would make an awesome mashup.
They say your handwriting is as unique to you as is your fingerprint. Maybe they are right – perhaps every person adds a little bit of his or her personality to their penmanship. Just maybe there are enough ways to vary pressure, speed, stroke, and a dozen other almost imperceptible factors that all 7 billion of us have a slightly different style.
The study of handwriting is called Graphology, and people have been at it for a quite a long time. Most experts agree that a person’s handwriting can reveal their gender, where it starts to get fuzzy is that others claim they can tell much more including age, race, weight, and even mood. Going further down the rabbit hole, some employers have tried to use handwriting analysis to determine if an applicant is a match for a position. That seems a bit of a stretch to us.
Now, if you want to digitize a tiny bit of what makes you, you – then all you have to do it to fill out this (PDF) form and upload it to the interwebs. Out the other end will pop a true type font that you can save for yourself or share with the world. Why would you want to do that? This hack caught our eye as a way of adding annotations to our work in a more informal, yet still personal manner. Or maybe we just wanted to upload it to the cloud in hopes it would live forever. Either way, if you want to see some really amazing style, head on over to the “Penmanship Porn” subreddit where you can find some amazing chicken scratch.
One of the hardest things in life is watching your parents grow old. As their senses fail, the simplest things become difficult or even impossible for them to do.
[kjepper]’s mom is slowly losing her sight. As a result, it’s hard for her to see things like the readout on the caller ID. Sure, there are plenty of units and phones she could get that have text-to-speech capabilities, but the audio on those things is usually pretty garbled. And yes, a smartphone can natively display a picture of the person calling, but [kjepper]’s mom isn’t technologically savvy and doesn’t need everything else that comes with a smartphone. What she needs is a really simple interface which makes it clear who’s calling.
Initially, [kjepper] tried to capture the caller ID data using only a USB modem. But for whatever reason, it didn’t work until he added an FSK–DTMF converter between the modem and the Pi. He wrote some Node.js in order to communicate with the Pi and send the information to the screen, which can display up to four calls at once. To make a mom-friendly interface, he stripped an old optical mouse down to the scroll wheel and encased it in wood. Mom can spin the wheel to wake the system up from standby, and click it to mark the calls as read. Now whenever Aunt Judy calls the landline, it’s immediately obvious that it’s her and not some telemarketer.
Rice is cultivated all over the world in fields known as rice paddies and it is one of the most maintenance intensive crops to grow. The rice paddy itself requires a large part of that maintenance. It is flooded with water that must be kept at a constant level, just below the height that would keep rice seedlings from growing but high enough to drown any weeds that would compete with the rice stalks for nutrients. This technique is called continuous flooding and a big part of the job of a rice farmer is to inspect the rice paddy every day to make sure the water levels are normal and there are no cracks or holes that could lead to water leakage.
This process is labor intensive, and the technology in use hasn’t changed much over the centuries. Most of the rice farmers in my area are elders with the approximate age of 65-70 years. For these hard working people a little bit of technology can make a big difference in their lives. This is the idea behind TechRice.
Continue reading “Sensor Net Makes Life Easier for Rice Farmers”