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Google Offers a Million Bucks For a Better Inverter

serbanp Re:so... (258 comments)

The input is DC so there is no need for low frequency input decoupling

Unfortunately, that's not true. The output is AC and the input-referred current will reflect it, i.e. will be quite high when the output reaches its highest (340V). Since the input source has an equivalent internal resistance of 10Ohm and would droop too much, some bulk capacitance is needed to provide these 120Hz current surges.

I agree with you that the design revolves around the placement of power components (capacitors, inductor, power switches and some sort of heatsinking), then the control circuitry be crammed in the spaces between them.

yesterday
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Google Offers a Million Bucks For a Better Inverter

serbanp Re:so... (258 comments)

Having read the actual spec, I realized that my question was stupid. Input voltage is 450V, therefore the inverter is just a full-bridge DC/DC converter

The challenge is actually perfectly doable, with the only difficult points being the size of the switching inductor and the input bulk (most likely tantalum) and output filtering (must be ceramic) capacitors. IOW, the winner will be the one with the best connections to component manufacturers.

2 days ago
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Google Offers a Million Bucks For a Better Inverter

serbanp Re:Why? (258 comments)

Having read the actual Spec Document, the input voltage is 450V DC, with an equivalent series resistance of 10Ohm. Definitely not 12V DC.

3 days ago
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Google Offers a Million Bucks For a Better Inverter

serbanp so... (258 comments)

what is the state of the art w.r.t. the 12VDC->110VAC/60Hz 1kW inverters?

3 days ago
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No Shortage In Tech Workers, Advocacy Groups Say

serbanp Re:it depends on what "skilled worker" means. (401 comments)

However, there are about 600,000 H1B workers in the USA. How many of these do you believe have the skills only found in comp-sci grad programs, or more to the point, how many of those don't have and don't need grad school comp-sci skills?

One thing I never understood is why so many posters on /. believe that Comp-Sci is the only highly technical field that matters. H1B visa holders are many times technically-educated people who have nothing to do with programming (i.e. Chemistry, Materials Physics, EE etc).

The Sun does not revolve around IT, so why are we suggesting it does?

about three weeks ago
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Nathan Myhrvold's Recipe For a Better Oven

serbanp Re:Hacking ovens? (228 comments)

I have half-bricks on the bottom of my gas-fired oven. It bakes much more evenly and keeps the temperature very steady.

Yes, thermal mass is the ticket, not just-in-time heat control gimmicks.

about three weeks ago
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Nathan Myhrvold's Recipe For a Better Oven

serbanp this guy is out of his mind (228 comments)

Not only it's not obvious what "better" means when baking is involved, but he's showing his Microsoft roots here, stupid "improvements" that make the whole system break so much easier.

It's a known fact that most "modern" residential ovens, the ones with displays, lots of buttons to set baking programs etc, should never use the self-clean cycle. The thermal insulation is not good enough to protect the electronics (a.k.a. control board) and the oven fails, typically after a high-heat cycle (the self-clean reaches 700-800*F). This is equally true for GE and Whirlpool as well as for Viking and Ilve.

Adding more electronics to a hot environment is asking for more and expensive trouble.

Commercial appliances are better built though, are they Myhrvold's target? In any case, his post is just a petulant rant showing overkill application of technology, just because "he can". Zapping mosquitoes with laser beams sounds more realistic...

about three weeks ago
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DNA Study: First Farmers Were Also Sailors

serbanp Re:Why not also Egypt? (40 comments)

However, the general consensus is that Egypt borrowed the agriculture invention, and rather late at that (~5000BC), not the other way around.

The Egypt's ancient culture has been focused on the Nile *exclusively*, they did not care about the delta and sea-faring until they started meddling in Middle East affairs (1200BC or so). The first major sea port has been founded in Classic Antiquity only!

about a month and a half ago
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Fasting Triggers Stem Cell Regeneration of Damaged, Old Immune System

serbanp Re:My friends don't fart... (148 comments)

My apologies, I was thinking of the colon. EFL (English as a fourth language).

Thanks for the correction.

about a month and a half ago
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Fasting Triggers Stem Cell Regeneration of Damaged, Old Immune System

serbanp Re:My friends don't fart... (148 comments)

Farting is caused by the inability of our intestine to break complex sugars (lack of specialized enzymes), examples of which can be found in legumes. These sugars then reach the gut, where bacteria have no problems breaking them, releasing gasses in the process.

There are even pills you can take with your food (e.g. when eating beans) that provide the missing enzyme so that you won't fart. In US, Beano is probably the most popular one.

You won't fart just because you ate a chocolate bar. And b.t.w., these complex sugars are not sweet, therefore there is no connection between eating sweets and farting.

about a month and a half ago
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Botched Executions Put Lethal Injections Under New Scrutiny

serbanp Re:Human's a very good at not dying (483 comments)

It must be a sad world in your neck of the woods or you're plain trolling. Gun ownership is much lower in Europe, you've been watching too many action movies "located" there.

I also don't see why you felt compelled to bring in the 2nd; the topic had nothing to do with it and nobody referred to it. Just take a deep breath and cool down.

about 2 months ago
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US Wireless Carriers Shifting To Voice Over LTE

serbanp Re:Seamless fallback (126 comments)

Unfortunately, the major carriers keep scaling down the voice repeaters to increase the data bandwidth instead. The network I'm on (Sprint) is getting worse and worse for pure voice calls, with new dead zones appearing very frequently - all in a metropolitan area.

Soon the voice service will be so bad you'll be happy to permanently switch to VoIP.

about 2 months ago
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Botched Executions Put Lethal Injections Under New Scrutiny

serbanp Re:Human's a very good at not dying (483 comments)

what's bollocks is your assertion that the relative crime rate in Europe vs. US has anything to do with the death penalty. Easy access to guns in US has much, much, much more to do with the crime rate.

about 2 months ago
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London Black Cabs Threaten Chaos To Stop Uber

serbanp Re:Customers are not property. (417 comments)

Finally an insightful comment! As opposed to the plethora of idiotic "buggy whip" vanilla bs.

about 3 months ago
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Ben Starr Answers Your Questions About Sustainability and Kitchen Tech

serbanp Re:Not Beer! (46 comments)

That's debatable. I like my wheat beer without any extra taste (including the acidic lemon wedge), so that I can enjoy the yeast, dough and bread flavors.

Hefeweiser is liquid bread indeed and I love bread...

about 3 months ago
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Interview: Ask Ben Starr About the Future of Food

serbanp Re:Local gardens and farms? (137 comments)

Chickens a make noise, all the time. They poop FAR more then you think, they're are stupid and do stupid things. They get diseases, there are predators, they die, they can fly over fences

.
I usually appreciate your comments but you're dead wrong about this subject.

In my block of SFH there are 4 people keeping chicken (myself included) and there is hardly any noise related to the chicken. The only noise they make is after they've laid an egg. No rooster allowed though.

If you keep the run dry (roof against rain and covered with absorbent things, such as straw), there is no smell at all from their poop, which anyway is not an issue.

Chicken are not stupid, especially if they live in decent conditions (not crowded, clean environment, fresh water, nutritious food, gentle handling etc). Some breeds are quite smart for a bird (Ameraucana comes to mind). Almost all will protect themselves from day predators (hawks etc), especially in a backyard context. At night, you keep the coop closed, so there's no risk.

If they're well fed, chicken will not be able to fly over a 8' fence once they're reaching adulthood (but maybe the bantam do).

As for diseases, they almost never get sick if properly cared for. Good food, enough room and clean coop/run go a long way in keeping the (vet.) doctor away.

about 3 months ago
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Interview: Ask Ben Starr About the Future of Food

serbanp Re:molecular gastronomy (137 comments)

yeah, that phrase sounds awfully pretentious, but This' book has some interesting bits about why some things work in the kitchen the way they do. Understanding why you're doing something when cooking makes you a better and more consistent cook.

about 3 months ago
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Interview: Ask Ben Starr About the Future of Food

serbanp Re:How do I (slowly) assemble my own awesome kitch (137 comments)

In the order of importance (for a residential setting):
1) good range or rangetop. The burners better be open style and capable of at least 15kBTU (22k and up to do wokking right)
2) good rangehood. At least 600-700CFM, baffle filters.
3) good oven, either in a range or stand-alone. Size is important, but evenness of baking is much more so. Steam capability optional.
4) good set of utensils. Many competing schools of thought regarding pans (I personally prefer cast iron in almost any situation), just avoid the non-stick coated thin aluminum junk. Good knives and even better knife sharpener.

Everything else is secondary, maybe the fridge/freezer are sitting on a distant #5.

Oh, and sous-vide is, i.m.o., overrated.

about 3 months ago

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