Day: August 1, 2018

Below, you’ll find the second installment of the After On interview with legendary tech publisher and prognosticator Tim O’Reilly. Please check out part one if you missed it. Otherwise, press play on the embedded player, or pull up the transcript—both of which are below.

Society has an insatiable desire for data. In fact, it is rather astonishing to think that average Internet traffic is several hundred terabits per second and consumes about eight percent of our electricity production. All of that for instant cat videos—and our desire for new cat videos is apparently insatiable, driving the need for more capacity and even more energy.

It would, however, be nice to scale capacity without energy requirements continuing to grow at the same rate. In a step toward achieving this goal, researchers have managed to encode an insane amount of information into the light of a single laser.

The problem with scaling bandwidth and power comes down to lasers and their inefficiency. A good laser is about 30-percent efficient. A typical telecommunications laser might emit 20mW, so that’s at least 70mW for each laser (the amplifiers consume even more energy). To pack more data into a single optical fiber, the data is divided across different colors of light, called wavelength division multiplexing. Unfortunately, each color requires its own laser, meaning the energy cost increases with bandwidth. 

Lasers with lots of colors

The researchers start in the same place that all optical communications systems begin: with a laser. But, instead of a very pure color, this laser emits pulses of light. These pulses are created by adding many very pure colors together, with the colors separated by evenly sized gaps in frequency. 

By itself, the laser doesn’t generate many of these colors, so the researchers use a trick to get more colors. The light is passed through a very fine wire (about 300 nanometers in diameter). The diameter is so small that the light is compressed and becomes very bright. The high intensity causes the material that makes up the wire to respond by generating new colors. The trick is that these new colors follow the spacing set by the laser pulse. So, out of the wire comes pulses of light that consist of thousands upon thousands of highly pure colors.

That means that a single laser generates all 80 colors required for the entire system, which is pretty cool. However, the researchers were not done yet.

Packing in the data

The emitted laser light is divided into two polarizations—polarization is the orientation of the electric field as it oscillates—so each color contributes two channels. Then, because the laser is pulsed, the information can be placed in four different time slots, called time division multiplexing. So, each color has a raw data rate of about 320Gbps. But, with 80 colors, that is 25Tbps.

The researchers were still not done.

The fiber that transported the signal consists of 30 light-guiding cores, surrounded by a single cladding. That means that each core is capable of transporting data at a rate of 25Tbps, bringing us to a grand total of 768Tbps. That, however, is the raw data rate. Data is always transmitted with some redundancy to allow for errors to be corrected, called forward error correction. Once redundancy is accounted for, the net data transfer rate is 661Tbps.

And that is an incredible amount of data by anyone’s standard.

As for power savings, I’m not really sure how significant they will be. Each data stream still needs to have independent modulation to encode the data, so there is no saving in power there. However, the laser itself emits less than 90mW, which is about five percent of the optical power that it would use if each color were emitted independently. Assuming that the lasers have the same efficiency—and that is a big assumption—then those savings will translate into electrical energy savings as well.

I can imagine this being a great energy saver within data centers and such. But, for long haul connections, I suspect the major energy cost is in the amplifiers. That said, no matter how you look at it, this is an excellent bit of engineering. 

Nature Photonics, 2018, DOI: 10.1038/s41566-018-0205-5

Welcome to another chapter in my ongoing saga entitled “big things are not small things.” In this edition of big vs. small, let’s look at hot stuff. Here I have three aluminum objects. A large block, a small block, and a heat sink.

Just for reference, the big block is about 14 centimeters long and the smaller block is almost 4 centimeters long (with the heat sink a little bit bigger than that). Of course none of these objects are cubes—but that’s OK. So here’s what I did. I put these in the oven for about an hour and then I took them out. Here’s what they look like (with an infrared camera).

In case you can’t tell, this shows the same three pieces of aluminum. Out of the oven, they are pretty hot (about 140 °C Celsius). I’m not sure why, but it looks like the smaller block is already significantly cooler. But anyway, they are hot. After an hour of sitting out of the oven, they look like this.

Notice how you can barely see the two smaller pieces? This is because they are about the same temperature as the surroundings. Yes, my garage is sort of hot right now. However, the large block is still quite warm—about 51 °C. Why? It’s because large objects aren’t the same as small objects.

Of course, that’s not a very good answer. Here’s a better one:

It may not be very surprising to say that hot objects eventually reach an equilibrium temperature with the surroundings. For an object like a block of aluminum, this thermal interaction can happen through thermal conduction (touching other objects) and thermal radiation. Let’s just assume that the blocks cool off primarily through radiation.

The Stefan-Boltzman Law describes the rate of energy output (the radiated power) for a particular object. This power depends on both the temperature and the surface area of the object. As an equation, it looks like this (assuming it is a perfect object that only radiates and does not absorb any external radiation).

In this expression, A is the surface area, T is the temperature and σ is a constant (not surprisingly called the Stefan-Boltzman constant). But of course the most important part is the area. If you double the area, you double the power.

OK, now let’s say I have two aluminum blocks. One block is 1 cm on a side (block A) and the other block is 2 cm on a side (block B). Both blocks start at the same temperature (let’s say 100 °C) and the cool down to 90 °C. I can calculate the area for both blocks to get the radiated power. Let’s do that.

• Block A area = 6 x (0.01 m)² = 0.0006 m² (each side is a square and there are six sides).
• Block B area = 6 x (0.02 m)² = 0.0024 m².

Since block B has a larger side, it has a surface area that is four times larger. This means that the power output is also four times larger. So, it would cool off faster? Right? Not so right. While it’s true that the bigger block has a faster decrease in energy, it also has more energy.

Let’s look at the change in energy for a temperature going from 100 °C to 90 °C. The energy change also depends on the object’s mass and the type of material. This can be described with the following equation:

In this expression, m is of course the mass and ΔT is the change in temperature. The other variable (c) is the specific heat. It is a measure of the change in energy per mass and temperature for a particular material. Aluminum has a specific heat of 0.9 Joules per gram per degree Celsius. But really, the specific heat doesn’t really matter since both blocks are made of the same material. What does matter is the mass. It’s the only thing that matters.

If you double the length of the side of a cube, what happens to the mass? Assuming a density of 2.7 grams per cubic centimeter, I will calculate the mass of these two blocks.

• Bloack A mass = (2.7 g/cm³) x (1 cm)³ = 2.7 grams
• Block B mass = (2.7 g/cm³) x (2 cm)³ = 21.6 grams

Yes, block B is eight times more massive even though it’s only double the length—that’s the way volume works. With eight times the mass, block B would need eight times the change in energy to go from 100°C to 90°C. So even though the radiated power is four times larger for block B, it will still take longer to cool off.

Like I said, when it comes to cooling stuff off—size matters.

Now for three examples in the real world.

• Muffins and cookies. Take a batch of cookies out of the oven. The smaller cookies will be cool faster than the big ones.
• The core of the Earth is much hotter than the core of the moon. One of the reasons—size. The Earth is much larger, so it takes longer to cool.
• Heat sinks. How do you cool off a computer CPU? You can use a heat sink. These are typically aluminum blocks cut in such a way to have a very large surface area. Larger surface areas means higher radiated power.

One last thing. What if someone wanted to find out how long it would take a super hot block of aluminum to cool down through only radiation? (Maybe it’s in deep space—I don’t know why.) It’s not such a straightforward solution to this problem. The rate at which it cools off depends on the temperature (via the Stefan-Boltzman Law) such that the cooling rate is not constant. One simple way to calculate the temperature is to break the problem into small steps of time. If the time step is small, then the power is approximately constant and I can use that to calculate the change in energy (and change in temperature).

Of course by breaking a problem into many smaller problems means that it’s going to be a lot of tedious calculations. I don’t know about you, but I like to skip over boring stuff—that’s why this is a perfect case for a numerical calculation with python.

So here you go. Here is a calculation of the cooling for the two aluminum blocks above. I did make one change—instead of starting at 100°C, they are are 500°C. Go ahead and look at the code (just click the “pencil” icon). Feel free to change stuff. You can’t break it.

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More Great WIRED Stories

ST. PAUL, Minn. — In what seems to be a magic trick, Dele Fayemi runs a batch of batteries in a beaker of boiling liquid — a physical impossibility that should cause a short circuit.

But instead of a highly dangerous combination of water and electricity, the 3M engineer is testing batteries in Novec, a non-conductive liquid the conglomerate has sold to cool supercomputers, and which it now aims to sell to automakers to cool batteries.

Maintaining a constant, low temperature helps electric vehicles (EVs) drive longer distances, so keeping batteries cool could help solve a key problem for automakers: A lack of range has been a major obstacle to the mass adoption of electric cars.

“As you can see, the temperature remains constant” for the batteries at 32 Celsius (90 Fahrenheit), Fayemi said, the boiling point of this particular batch of Novec, which 3M also wants to sell to data centers to keep servers cool.

“Automakers are trying to figure out how to get the absolute maximum out of batteries,” said Ray Eby, head of 3M’s automotive electrification program, which was created last year. “That’s right in 3M’s wheelhouse.”

Major automakers plan to roll out hundreds of new electric vehicle models over the next several years, fueled by investments that consultancy AlixPartners has estimated at up to $255 billion through 2023.

To put that in context, in 2017 all the world’s automakers and suppliers combined invested $115 billion in research and development, and had capital expenditures of $234 billion.

Much of that investment will flow to suppliers, but only if they can offer ways to cut electric vehicle manufacturing costs, which are still higher than for internal combustion cars. 3M and other automotive technology companies are looking for ways to adapt to electric vehicles existing products that enjoy economies of scale from other markets.

Along with major suppliers like BorgWarner and Aptiv, others like aluminum company Norsk Hydro ASA and synthetic rubber maker Trinseo SA are developing products to extend the driving ranges of electric vehicles, attacking a significant barrier to higher sales.

Suppliers hope automakers will adopt their technology early in the development process so they can sell similar products to more than one customer.

‘Big, big investment’

With no set approach to developing EVs, automakers are pursuing their own paths, giving suppliers a once-in-a-lifetime opportunity to influence what parts and even what materials to use.

“Eventually we’ll see more standardization in the high-voltage market, but it’s not there yet,” said Alan Amici, vice president of transportation solutions for TE Connectivity Ltd.

That’s why TE and other suppliers using embedded teams of engineers within the engineering operations of major automaker customers. From inside, suppliers can pitch existing products and materials, or ones they have in development.

Their customers are looking for ways to get more driving miles per charge, tackle technical problems such as electromagnetic interference or, most important, cut costs on vehicles that are as yet unprofitable.

St. Paul-based 3M formed its automotive electrification group as global automakers rolled out ambitious investment plans, the bulk of which are earmarked for China. The Chinese government has enacted escalating electric-vehicle quotas starting in 2019.

3M will not disclose its spending on EV technology, but executive chairman Inge Thulin says it is a “big, big investment.”

The company has already provided “thermal management” technology for General Motors’ Bolt EV to extend its range.

Taiwanese auto startup Xing Mobility is using Novec to cool the batteries in its high-performance Miss R model, and 3M says other automakers are working to adopt the technology, but declined to disclose names.

3M also aims to repurpose filter technology used in cellphones for EVs to make infotainment screens and consoles brighter while at the same time using less energy, helping boost battery range.

It also has technology, again from cell phones, to cut electromagnetic interference — enabling EVs, for instance, to drive under power lines without various functions cutting out.

Lighter goes farther

Making vehicles lighter extends EV range.

Norsk Hydro, which already supplies Tesla, is figuring out how to marry up products from two of its own businesses, extruded body-frame parts and precision tubing, to develop new ways for cooling battery packs, said Mike Tozier, who leads Hydro’s advanced product development in North America.

That way, Hydro should be able to provide automakers with more ways to lighten their loads and thus make aluminum a more attractive choice.

“Automakers are more comfortable with steel, so you’re automatically fighting an incumbent material there,” Tozier said. “But automakers are looking aggressively at more options because they have to remain cost competitive at high volumes.”

The push to find ways to add to EV range extends down to the tires.

Trinseo has invested in a plant in Germany that will increase its synthetic rubber production capacity 33 percent to meet anticipated growth in electric vehicle production, and will help the supplier develop more efficient products. Tires made with synthetic rubber can already boost efficiency by 12 percent compared to conventional tires, said Hayati Yarkadas, a senior vice president at the company.

“The development cycle requested for EVs is significantly shorter and faster than what we have faced with the traditional automotive industry,” he said.

Reporting by Nick Carey

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