Category Archives: STEM

Science, Technology, Engineering, and Mathematics

Matchstick-sized sensor can record your private chats

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Conventional microphones work when sound waves make a diaphragm move, creating an electrical signal. Microflown’s sensor has no moving parts. It consists of two parallel platinum strips, each just 200 nanometres deep, that are heated to 200 °C. Air molecules flowing across the strips cause temperature differences between the pair. Microflown’s software counts the air molecules that pass through the gap between the strips to gauge sound intensity: the more air molecules in a sound wave, the louder the sound. At the same time, it analyses the temperature change in the strips to work out the movement of the air and calculate the coordinates of whatever generated the sound.

via Matchstick-sized sensor can record your private chats – 26 September 2013 – New Scientist.

Acoustic Vector Sensors

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In acoustics this movement of air is called particle velocity. The Microflown sensor is based upon MEMS technology, and uses the temperature difference in the corss section of two extremely sensitivy platinum wires that are heated up to 200°C in order to determine Acoustic Particle Velocity. When air flows across the wires, the first wire cools down a little and due to heat transfer the air picks up some heat. Hence, the second wire is cooled down with the heated air and cools down less than the first wire. A temperature difference occurs in the wires, which alters their electrical resistance. This generates a voltage difference that is proportional to the Particle velocity and the effect is directional: when the direction of the airflow reverses, the temperature difference will reverse too.

via Overview – Acoustic Vector Sensors – Microflown AVISA.

“Synthetic Tracking” Set to Revolutionise Near-Earth Asteroid Discovery

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By contrast, they say that with a 5 metres telescope, synthetic tracking should spot about 80 of these objects each night. That’s “almost 1000 times higher than the discovery rate of these small objects over the last 5 years,” they say.

via “Synthetic Tracking” Set to Revolutionise Near-Earth Asteroid Discovery  — The Physics arXiv Blog — Medium.

But there are other uses for this data. NASA is hoping to send a crewed mission to a near Earth asteroid in the not-too-distant future and has started a program called the Asteroid Grand Challenge to identify potential targets.

Paper on this subject here.

The Post-Lecture Classroom: How Will Students Fare?

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A three-year study examining student performance in a “flipped classroom” — a class in which students watch short lecture videos at home and work on activities during class time — has found statistically significant gains in student performance in “flipped” settings and significant student preference for “flipped” methods.

via The Post-Lecture Classroom: How Will Students Fare? – Robinson Meyer – The Atlantic.

“And with this,” she said, “you actually have to do reading or watch the [lecture modules], you actually have to prepare for the class.”

The Feynman Lectures on Physics

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Caltech and The Feynman Lectures Website are pleased to present this online edition of The Feynman Lectures on Physics. Now, anyone with internet access and a web browser can enjoy reading a high-quality up-to-date copy of Feynman’s legendary lectures. This edition has been designed for ease of reading on devices of any size or shape; text, figures and equations can all be zoomed without degradation.1

via The Feynman Lectures on Physics.

New connection between stacked solar cells can handle energy of 70,000 suns

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Stacked solar cells consist of several solar cells that are stacked on top of one another. Stacked cells are currently the most efficient cells on the market, converting up to 45 percent of the solar energy they absorb into electricity.

via New connection between stacked solar cells can handle energy of 70,000 suns.

This should reduce overall costs for the energy industry because, rather than creating large, expensive , you can use much smaller cells that produce just as much electricity by absorbing intensified from concentrating lenses. And concentrating lenses are relatively inexpensive,

Gear up for the school year with these open source applications

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Here are five great open source applications for learning. Share this list to your favorite student or teacher!

via Gear up for the school year with these open source applications | opensource.com.

Play with math, programming, music, and art in the powerful Kojo Learning environment. Based on ideas derived from innovative programs such as Logo and Geometers Sketchpad, Kojo offers a rich platform for students to explore the synthesis of mathematical ideas, coding, creative thinking, and learning.

Weak Keys in Network Devices – Mind your RNG!

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An RSA public key (e,N) consists of an exponent e and a modulus N. The modulus is the product of two randomly chosen prime numbers p and, q. If p and q are known, it is straightforward to derive the private key. However, if they are unknown, one must factor N into p and q, which requires intensive computing resources. However, let’s assume that two keys with modulus N1 and N2 share one of the factors: N1 = p1 x q and N2 = p2 x q. In this case, finding the greatest common divisor of N1 and N2, which is q, is sufficient to factor these two moduli. The task of finding the greatest common divisor of two 1024-bit integers is much simpler than factoring and can be done in microseconds…

This well known vulnerability of RSA can be exploited in the context of low entropy keys. Poor random number generation can indeed lead to multiple keys sharing one of their factors. Heninger found that more than 60’000 keys (approximately 0.5%) they had collected could be factored in this way.

via Quantis Newsletter – September 2012.

Qcloud puts quantum chip in the cloud for coders to experiment

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The team behind the project believes that the limited availability of quantum computers would deter extensive research and there would be shortage of skilled quantum researchers, engineers and programmers once quantum computers actually make it to the main stream. Through Qcloud the team is keen to open up quantum computing research and make it available to as many researchers, engineers, entrepreneurs and engineers as possible.

via Qcloud puts quantum chip in the cloud for coders to experiment.