dskhatri

tldr: We made an air disinfection system that can in real-time mitigate the spread of respiratory infections indoors. In the Show HN spirit, happy to show the system to those in Los Angeles!

Incorrect. They have done it: http://ackinetics.com/wp-content/uploads/AC-Kinetics-60Hp-Tr...

No. AC Kinetics appears to offer significantly improved efficiencies over VFDs: http://ackinetics.com/wp-content/uploads/AC-Kinetics-60Hp-Tr...

[1] https://www.treasury.gov/resource-center/data-chart-center/i...

There are interesting non-metallic materials already in large-scale production which serve as excellent heat sinks and pipes. As an example, pyrolytic graphite has a thermal conductivity several times greater than that of Cu: https://www.mouser.com/m_new/panasonic/panasonicthermalgraph...

See Murata's Robots: http://www.murata.com/en-us/about/mboymgirl

Just tap the pull-down menu button in the volume dialog and change the appropriate volume slider.

Perhaps a combination of factors? He was born in Cambridge, MA. MIT celebrated 100 years in the city. And Good Will Hunting.

The radar chip central to Project Soli is developed by Infineon Technologies

http://www.infineon.com/cms/en/product/promopages/soli/

http://www.infineon.com/dgdl/InfineonGoogleSoliFAQEnglish.pd...

I read an article in the WSJ saying the Model 3 will be steel based instead of Al based like its bigger siblings. Heavier vehicle..

* Article title is "A Lot Riding on Tesla's Model 3 Unveiling"

B.P. Abbott must be getting a lot of inquiries :)

Edit: Abbott is, when alphabetically arranged, the first name of a long list of authors.

I believe this was invented by a Washington State-based company, Inventist. They also came up with the Electric Unicycle (EUC).

http://www.inventist.com

In the tight parking spot scenario, how does the driver get out of the car?

Packaging is indeed critical to get heat out. There have been some cool (no pun intended) developments on this front such as the DirectFET [1], LFPAK [2]

[1] http://www.irf.com/technical-info/whitepaper/directfet.pdf [2] http://www.nxp.com/documents/leaflet/939775016838_LR.pdf [3]

Both depletion-mode and enhancement-mode GaN devices exist now. The former can be turned into a "normally off" device by combining it with a low voltage Si FET to form a cascode [1]

[1] Slide 36: http://www.irf.com/product-info/ganpowir/gangeneral.pdf

GaN provides a couple of benefits compared to Silicon:

1. It offers a lower on-resistance for the same breakdown voltage as a silicon device [1].

2. It offers a lower gate charge which allows you to turn it on and off at a much higher frequency than Silicon devices [2]

(1) means you have lower losses in a power circuit with GaN vs Si (leading to more compact - smaller heat sinks - power supplies for example)

(2) means power supplies can run at much higher frequencies. At higher frequencies, you can use smaller inductors and capacitors which means more compact circuits.

A practical example of GaN in action is FinSix' Dart power supply [3]

[1] Slide 5 of http://www.irf.com/product-info/ganpowir/gangeneral.pdf [2] http://m.eet.com/media/1179793/si-vs-gan-vs-sic-which-proces... [3] http://finsix.com/dart/

Germany has a sophisticated spy program of its own: http://www.theguardian.com/commentisfree/2013/oct/04/german-...

Where did you buy it from at $300? How does it perform uphill?

I would be more concerned about me smashing into a tree at 40mph than the bike. 40mph is an exaggeration, isn't it?

The marshmallow experiment results are not as clearcut as the article implies: http://www.washingtonpost.com/blogs/wonkblog/wp/2012/10/13/t...

His point is more about not putting all your eggs in one basket; you certainly don't tell your barista about an upcoming physician's appointment, or that you are in the market for a house. Your barista is also disconnected from parties who may leverage the information you provide him/her. Similarly, you don't tell your broker that you prefer Ethiopian coffee. Google offers so many services that it has a much broader insight into who you are. To the privacy-conscious, that's an unacceptable fact. Nothing to be pained about.

What an interesting and unique approach to online discourse! In general terms (not asking to reveal the secret sauce), how do you define the opinion groups? Latent Semantic Analysis?

The output of a solar array is a DC voltage (constant over time). Our homes are fed by an AC voltage (varying sinusoidally over time at a frequency of 60Hz).

A circuit is needed to convert the DC to AC. There is a loss in energy due to the functioning of the circuit. The circuit size and complexity depends on the specifications of the DC to AC inverter including the maximum power capability desired.

Traditional converters operate at low frequencies and lose a lot of energy due to the technological limitations of the semiconductors switches used. The switches essentially chop the DC input into a square-wave type output of a frequency in the low kHz range. This square wave output needs to be low pass filtered to allow only the 60Hz to propagate through to the inverter output. For low kHz type square wave, the inductors and capacitors used to make the low pass filter are large.

New semiconductor technology has resulted in switches that can operate at MHz frequencies. The inductor and capacitors used to make the low pass filters can be much smaller for MHz frequencies. These switches also have much lower conduction losses than the previous silicon-based switches but they need to be used in more novel topologies in order to minimize what are called switching losses.

To see a real-world example of what improvements can be made with the new semiconductor technology, compare the brick power supplies that come with our laptops to the much touted FINsix Dart (http://finsix.com/dart/). The latter uses new GaN switches that operate in the MHz range AND a novel topology that minimizes switching losses.

FINsix solved a AC-DC power converter problem. This is a DC to AC inverter problem.

There are all sorts of specifications/requirements listed (box size, ripple allowed, EMI limits) but the most interesting that is not mentioned is cost. There is no upper limit set on the BOM cost.

You still need DC-DC conversion. High voltage DC transmission is already used in some parts of the world [1]

[1] http://en.wikipedia.org/wiki/High-voltage_direct_current

Some solutions to the problem will utilize a high frequency, high voltage switching inverter. The performance of this type of inverter is limited by the losses generated by the devices making up the inverter. The wide bandgap devices (switches in essence) offer the lowest losses for this type of topology. Furthermore, some novel inverter designs work only if they operate at very high frequencies. Only the wide bandgap devices can switch at these high frequencies.

Another solution is to use soft-switching (zero-current or zero-voltage switching) methods.

See arduboy, covered previously: https://news.ycombinator.com/item?id=7325486

http://bateske.com/arduboy/

Yep, Permanent Magnet AC (PMAC) motors are common types of synchronous motors. They are generally more compact than induction motors for the same power output. Induction motors are generally less expensive.

An official (not forum post) article comparing the two: http://www.teslamotors.com/blog/induction-versus-dc-brushles...

DC Brushless and PMAC are interchangeable. Oh, and nowadays, you don't need sensors (hall, encoder etc). 'Sensorless' motor control is possible by sensing the back emf of the motor or reconstructing the motor current via (super inexpensive) shunt resistors on the legs of the inverter.