Why Wind Turbines Have Three Blades - <AUTHOR> http://www.cringely.com/2016/05/06/15262/ <comment><USER3> Three blades is the smallest number that reduces the vibrations due to the blades crossing the support structure. When a blade crosses the support its applied force is reduced because the wind is slower around the support. This reduction in forces creates a yawing torque that can lead to unwanted vibrations. Much of the structural stiffness and bearing requirements are related to these effects. Three blades minimizes the effect because when one blade crosses the support the other two blades are out in a Y shape, shortening the force differential when compared to two blades.

<comment> mark-r There's a question then, why are support towers solid? Maybe they should be made more like the Eiffel Tower?

<comment><USER4> Because a lattice tower has much worse properties when it comes to interacting with the wind. The behavior of the air behind the rotor is as important as getting quality air to flow through the rotor.

Some early windparks used lattice towers, and some of those survive to the present but they are now known to be worse performance wise than tubular towers.

<comment><USER5> A Shukhov tower [0] has minimal wind loading, due to its hyperboloid sections.

[0] [https://en.wikipedia.org/wiki/Shukhov_Tower](https://en.wikipedia.org/wiki/Shukhov_Tower)

<comment><USER4> That profile is not very well suited to having a windmill on top of it. The problem is that the nacelle is tilted backwards only a few degrees so you need a very slender tower (or you'll have tower strikes in high winds).

<comment><USER5> The cooling towers of a nuclear plant follow the same principle. The sides are formed from straight structural members angled in opposite directions (doubly ruled), and the gaps are filled with concrete.

The profile of a hyperbolic wind tower may be altered such that the cross section at maximum height minus blade radius is at a minimum. The largely conical profile of the existing Shukhov towers were used for power transmission lines and a radio broadcast antenna.

Check this out: [http://www.pbs.org/wgbh/nova/next/tech/proposed- hyperboloid-...](http://www.pbs.org/wgbh/nova/next/tech/proposed-hyperboloid- energy-skyscraper-uses-simple-math-to-solve-a-big-problem/)

<comment><USER4> Interesting! You'd think that the major wind power manufacturers would have looked at all possibilities. One major immediate concern is that these look quite ugly and fat compared to the relatively thin and slender supports that the latest generation of turbines uses. I'd love to see a side-by-side comparison of these towers and the various alternatives.

[http://cache1.asset-cache.net/gc/78480146-crowley-ridge- wind...](http://cache1.asset-cache.net/gc/78480146-crowley-ridge-wind-power- alberta-canada- gettyimages.jpg?v=1&c=IWSAsset&k=2&d=wW%2BWqJ5Jns5%2FhtycaQeRKiwHOo%2B1W%2FQabqSCG%2F1%2FRWnbLBlDKuH8j9bn4OWw4zSv)

Is one example of lattice towers in production that I know of (but not like the ones you describe and I have never seen those being used for windmills).

<comment><USER5> As mentioned in Jobs quote near the top of the article, you often find that people tend to do things in a certain way just because that is what has been done before. No one bothers to experiment because the old way has always been good enough.

This is why is is sometimes difficult to avoid premature optimization, because post-maturity optimization tends not to happen, even when it may be warranted. I know of no wind farm anywhere that is used for side-by-side comparisons of wind turbine technologies. It would very likely have to be owned by a university and supported by public funds.

I have never seen a hyperboloid lattice or diagrid structure in person, but they are not entirely unheard of for shapes that do not require a lot of space efficiency in the tower portion, such as for lighthouses, observation decks, water towers, radio towers, etc.:

[https://en.wikipedia.org/wiki/Adziogol_Lighthouse](https://en.wikipedia.org/wiki/Adziogol_Lighthouse)

[https://en.wikipedia.org/wiki/Kobe_Port_Tower](https://en.wikipedia.org/wiki/Kobe_Port_Tower)

[https://en.wikipedia.org/wiki/File:Ciechanow_water_tower.jpg](https://en.wikipedia.org/wiki/File:Ciechanow_water_tower.jpg)

[https://en.wikipedia.org/wiki/Corporation_Street_Bridge](https://en.wikipedia.org/wiki/Corporation_Street_Bridge)

[https://en.wikipedia.org/wiki/Aspire_Tower](https://en.wikipedia.org/wiki/Aspire_Tower)

[https://en.wikipedia.org/wiki/Canton_Tower](https://en.wikipedia.org/wiki/Canton_Tower)

<comment><USER6> >No one bothers to experiment because the old way has always been good enough.

If you are a manufacturer though, you have all of the incentives to come up with something more efficient though. Wind turbines aren't controlled by a monopoly are they?

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER7> This is only partially related to my other long post here, but it should be mentioned. This article appears to be largely about potential to disrupt the wind industry with outside the box thinking. But in the more than a decade I have been working in this industry the single most disruptive change in project performance was targeting low wind speeds rather than high, and accepting that turbines will have to shut down in higher winds.

The main way this is achieved is to take a huge rotor and put it on a small generator. More energy is lost at high winds, but the ramp up from no generation to maximum is much faster. Since most projects spend the majority of their time along that ramp rather than at rated power this results in large gains in annual energy.

This means that some sites once considered to be marginal to end up being good to very good. One area I've been working in saw a more than 25% increase in predicted energy for the same capital cost with the new turbine types.

<comment><USER8> I'm not in the wind industry and am not a ME, but rather a EE, but why couldn't you build a big vertical-axis wind turbine and then couple that to multiple generators, a big one and a small one, with gearing that lets the windmill drive either one? Then in low winds, you can drive the small generator at its optimal speed range, and then in high winds, you can switch over to the big generator and drive it at its optimal speed range (the small generator is decoupled in this mode).

Obviously, this would be much more costly because of the additional big generator and the complication of the drivetrain. But it'd let you harvest a bunch of energy when it's really windy. And with a vertical-axis mill, not only would this be better for wildlife (lower overall speeds), the generators would be on the ground, not way up in the air, and driven by a shaft from the mill through its tower, so servicing would be easier and the weight and size of the generators and the drivetrain wouldn't be an issue.

<comment><USER9> I think you've misunderstood the innovation. The innovation in using a generator that is smaller than the blades and tower are capable of supporting isn't in the light-load efficiency of the generator. Its in the lower capital cost of the electrical system.

</comment></comment></comment><comment><USER10> * I don't understand his explanation of starting torque. You can jump-start that problem by other means in the alternator. Torque and power should be decoupled anyway by blade pitch.

* There is such a huge difference between a 12m blade and a 60m blade that I don't see how the comparison is at all relevant. We played with smaller turbines for _decades_ before we reached this sort of price efficiency.

* Betz' law explicitly disavows picking a number of blades: "Assumptions: 1. The rotor does not possess a hub and is ideal, with an infinite number of blades which have no drag. Any resulting drag would only lower this idealized value. ..."

* Betz' law is a three-dimensional consequence of convervation laws, not an observation about turbulent blade interactions. "Consider that if all of the energy coming from wind movement through a turbine was extracted as useful energy the wind speed afterwards would drop to zero. If the wind stopped moving at the exit of the turbine, then no more fresh wind could get in - it would be blocked. In order to keep the wind moving through the turbine there has to be some wind movement, however small, on the other side with a wind speed greater than zero. Betz' law shows that as air flows through a certain area, and when it slows from losing energy to extraction from a turbine, it must spread out to a wider area. As a result geometry limits any turbine efficiency to 59.3%."

* We already have a good idea what a moderate redesign of the fundamentals of a wind turbine looks like; It points downwind, it's huge like the existing turbines, and its two blades bend. They just need to solve the tower strike problem. [https://www.technologyreview.com/s/401583/wind-power-for-pen...](https://www.technologyreview.com/s/401583/wind-power-for-pennies/) [https://www.technologyreview.com/s/528581/two-bladed-wind-tu...](https://www.technologyreview.com/s/528581/two-bladed-wind-turbines-make-a-comeback/)

<comment><USER9> > I don't understand his explanation of starting torque

That's because Cringley doesn't, either. The starting torque is entirely provided by the wind, not the grid.

<comment><USER11> I think what he's talking about (not bothering to re-read) is the power required to magnetize the alternator components in the first place, so the alternator works at all. They use electromagnets rather than permanent magnets, because electromagnets are much cheaper, especially at that size. This is a fixed power requirement, so if the alternator can't generate more than that fixed power need to operate, there's no point in running.

<comment><USER9> Magnetizing power (and other constant-term losses) are a very small portion of the rated turbine power in a doubly-fed induction generator (DFIG).

Edit (one more thing): At this scale, permanent magnet (PM) machines aren't much more efficient than DFIG machines. It turns out that eddy current losses in the stator back iron remain as a significant term in both machines. But for a DFIG machine, the eddy current losses at light load are reduced by quite a bit relative to the losses produced by a PM machine. Since real-world wind turbines end up operating at partial load for much of their life, the effects basically wash out, or are even a net negative for the PM machine.

</comment></comment></comment></comment><comment><USER12> This is a classic example of sub-optimization (and even if it's hand-wavey pseudo-science and may be wrong, the general concept is still interesting).

Each individual wind turbine is optimized to be the "most efficient" it can possibly be.

But not in the context of the environment, which requires complex control systems and methods to reduce damage in non-optimal conditions.

And not if you take cost and efficiency of the whole system into account; where four times as many small turbines with less complexity run more often and produce more overall output.

But hey, each wind turbine is "optimal." Interesting.

Most complex systems have this property. Even (especially?) your business.

<comment><USER13> This kind of thinking contributed to American rocketry being trapped in a local maxima for decades. There are many reasons it became trapped, but one of the primary reasons was that rocket scientists would insist on optimising rocket engines at the expense of every other aspect of the vehicle.

"The logic of rocket equation is brutal and inexorable", the NASA rocket scientists would say. "As the performance of the rocket engine decreases linearly, the propellent requirements increases exponentially. Therefore it is imperative to have the highest-possible performance from your rocket engines. The combustion of liquid hydrogen / oxygen is the highest-efficiency chemical reaction, and therefore liquid hydrogen is the only propellant we will consider using for our engines."

All of this was correct, but also _wrong_. It was wrong in a whole-systems context, because:

A.) Liquid hydrogen is much lower-density than traditional rocket fuels like Kerosene, requiring far larger and heavier structures to carry the same amount of energy, and larger and heavier engines and plumbing and everything else -- and the structural mass of a rocket _matters_.

B.) Liquid hydrogen will boil off and leak through anything, requiring massive amounts of insulation (again, adding weight), and far stricter operational protocols around the fueled vehicle.

C.) Liquid hydrogen is so cold that it will embrittle and shatter ordinary metals and requires much more exotic and expensive metallurgy.

and finally, D.) The alternative, kerosene, gives you less efficient engines but also much lighter-weight vehicles -- and sure, per that inexorable logic of the rocket equation, you need to use more fuel for the same amount of payload, but kerosene is _cheaper than milk_ so who fucking cares?

Anyhow, the upshot of this is that US rocket scientists spent literally tens of billions of dollars developing hyper-locally-optimised rocketry schemes, most of which failed outright. For the remainder, for every dollar of kerosene they didn't have to buy, they probably spent upwards of $1000 on exotic aerospace hardware. Finally, they gave up and just bought kerosene-based engines from the Russians.

So then there's Elon Musk. And of course there's a ton of brilliant rocket science in the Falcon, but much of the reason for SpaceX's success is because it doesn't optimise _solely_ on the rocket science. They optimise for cost as a whole, and consider factors like design, manufacturing, operations, reusability, etc. to be relevant to the question of cost.

For example: the Falcon 9 would undoubtedly be more efficient if it had a hydrogen-based upper stage. But doing that would cause it to lose most of its commonality with the lower stage, requiring an entirely new design, manufacturing, and operations workforce. Which would cost several orders of magnitude more than the extra kerosene required to fly a "sub-optimal" rocket. The reason they've already cut the price of launch by about 80% vs. (say) the Space Shuttle is because they optimised the _whole system_ , keeping the unique part count and operational complexity as low as possible.

I still sometimes hear old-school rocket scientists grumble about how the Falcon is a less optimised vehicle than the Shuttle, though. They just don't get it. Never will.

Anyhow, that was a tangent. Fascinating to think that wind turbines might be amenable to a similar class of disruption.

<comment><USER14> > Anyhow, that was a tangent

It's also untrue, US rocketry kept varied propulsion types throughout its history including both RP1-only and LH2-only as well as mixed stages, HTPB and Aerozine. Your painting of rocket scientists as some sort of confederacy of dunce unable to get a grip on tradeoffs is not only inane it's insulting bullshit.

<comment><USER15> I started reading _Ignition!_ and it is a _hoot_. I really get the impression that the rocket fuel scientists fixated, not because of personal issues (though hilarity ensues there), but because the search space is damn large (at least while still discovering how fuels interacted). Or worse, it just takes a damn long time to even properly test. So when you found something promising, you really dug into it.

<comment><USER16> Yes, it's a fantastic book. Not necessarily a good role model for future work, but it perfectly captures the spirit of rocket science at the time: [http://library.sciencemadness.org/library/books/ignition.pdf](http://library.sciencemadness.org/library/books/ignition.pdf)

Everyone who grew up idolizing rocket scientists should read it. If you have problems with missing pages or broken figures, try a different PDF viewer. The PDF has something odd about it that confuses some in-browser viewers.

</comment></comment></comment></comment></comment><comment><USER17> Erm, I don't know if I trust Cringely when it comes to this sort of thing. He sold a reality show to PBS, "Plane Crazy (1998)"[1] with the promise he could design and build a small plane in 30 days that was unlike any other that had ever been built.[2]

His engineer just flat out refused to produce any plans for this design. He tried to make something like his plane happen anyway, going without sleep for weeks, and had a meltdown on camera. The show eventually had to be about him giving up on his cherished design and building a throwback to biplanes, with a family of artisans who are experienced in building them.

I had the feeling that Cringely was trying to channel Steve Jobs and it didn't work out. (Note: Jobs drives _other_ people to do impossible missions without sleep, not himself, and doesn't display his work until it's ready, giving the appearance of effortless superiority).

Anyway as for this wind farm idea, the evidence of his friend's alternative propeller design is interesting. But let's also note that that this friend chose not to pursue wind farms, maybe for a reason.

[1] [http://www.pbs.org/cringely/pulpit/1998/pulpit_19980724_0005...](http://www.pbs.org/cringely/pulpit/1998/pulpit_19980724_000578.html)

[2] EDIT: I am not an aviation person, and my memory of this is poor, but from Googling I see apparently he wanted to make it out of unusual materials, have foldable wings, and put the engine behind the pilot. I have a memory of his design requiring the pilot to straddle the drive train to a front-mounted propeller. I don't know how problematic that is, but I remember it as being presented as a major problem.

EDIT 2: To be honest I feel a bit bad now about this being a top-voted comment, as Cringely learned a lesson on camera that many startup people learn behind closed doors – confidence is great, but trying to innovate in too many directions at once will kill you. Maybe that means that he is more cautious now, so perhaps he's _really_ sure this thing will work. On the other hand, it was the first thing I thought of, that maybe he doesn't have a great track record with aviation iconoclasm.

<comment><USER18> > His engineer just flat out refused to produce any plans for this design Do > you know why? I'm thinking maybe it's because it was dangerous for the > pilot?

<comment><USER17> Sorry, I'm relying on my memory of a show I saw like 20 years ago. I know nothing special about aviation. But I just found a contemporary thread about it here from other homebuilt aviation enthusiasts.

[https://groups.google.com/forum/#!topic/rec.aviation.homebui...](https://groups.google.com/forum/#!topic/rec.aviation.homebuilt/0uMOHlci8DQ)

</comment></comment></comment><comment><USER19> Slightly relevant, here's a really weird wind turbine designed by a computer: [http://m.youtube.com/watch?v=YZUNRmwoijw](http://m.youtube.com/watch?v=YZUNRmwoijw)

<comment><USER20> The note on the video is quite funny:

Note: I have since discovered I used the wrong viscosity for air on this experiment, so the results aren't valid for use on the earth. (Maybe Jupiter.)

<comment><USER19> Ah, well. It's still interesting. The design of the turbine is really crazy and not what I would have expected in any environment. So I suspect if he corrected the parameters, it would still come up with a crazy and clever design for Earth use, that humans wouldn't think of.

</comment></comment></comment><comment><USER21> I'm not saying he is wrong, but he makes some bold claims without giving any proof.

Some examples:

> Twelve blades is a nice number.

Why twelve? Why not 50, it's a nice number as well.

> Lipps turbines can operate in faster winds [...] turbines could be allowed > to run 24/7 in any wind with no computer

So even in the strongest winds turbines with 40 feet blades do not need to be stopped?

> using permanent magnet generators instead of alternators, but those are more > expensive > Use permanent magnet generators leading to [...] even lower > cost.

Which is it now?

> what matters isn't power efficiency per turbine so much as power production > per acre of wind farm.

Isn't it rather electricity production efficiency in terms of invested capital?

<comment><USER22> I get the feeling that the best answer to the question is that empirical testing (perhaps by simulation) points out that three is the optimal number of blades.

This leads me to the question: is it possible to determine a good rotor design by using optimization techniques such as simulated annealing or genetic programming? Or are the simulations too costly?

<comment><USER23> I can help with this a bit.

The simulations are quite difficult - flow simulation is well-established, but it's a big step from that wind farms. You need to simulate many turbines interacting at a specific site, under a variety of conditions. That's not the problem with modeling single turbines, though.

Rotor design is hard to simulate productively for the same reason that Cringely's analysis is flawed: many of the biggest factors are unrelated to everyday running.

\- Even blade counts create resonance patterns that stress your tower.

\- High solidity designs suffer more stress in storms (even while stopped), so they break more

\- Noise interferes with putting rotors near houses or over pastures

\- Storage is difficult and consistency is valuable, so expanding the operating range up to high winds is less useful than expanding it down to low winds

And so on. If you model pure efficiency, the sims are pretty easy. If you model real value, you either can't do it, or you get a search space so jagged that finding maxima is hopeless.

</comment></comment></comment><comment><USER24> Looks like a fine opportunity to ask - whatever happened to vertical axis wind turbines?

They sounded like they had a bunch of advantages, not least a much higher tolerance for extreme wind conditions, less stress on long (suspended) blades, possibly less gearing issues in translating motion back to the ground - <USER2> presumably they had / still have distinct disadvantages?

<comment><USER25> Even sexier (and less field-tested) than vertical turbines are windbelts.

[https://en.wikipedia.org/wiki/Windbelt](https://en.wikipedia.org/wiki/Windbelt)

> Prototypes of the device are claimed to be 10 - 30 times more efficient than > small wind turbines. One prototype has powered two LEDs, a radio, and a > clock (separately) using wind generated from a household fan. The cost of > the materials was well under US$10. $2–$5 for 40 mW is a cost of $50–$125 > per watt.

</comment></comment><comment><USER26> We all love the story about the clever little guy who thinks outside of the box taking down the big giant corporation who does things the way they have always been done. Cringely trys to tell this as such a story, or could be, or could have been. But there is really no evidence backing it, just his desire to tell a good story.

</comment><comment><USER27> One graph is worth thousand words.

Rotor power coefficient vs. tip-speed ratio.

[http://i.imgur.com/PONHerZ.jpg](http://i.imgur.com/PONHerZ.jpg)

<comment><USER28> You have a computer with servos and winches fly parafoil kites to generate power from wind. This is definitely the theoretically optimal answer. It's also very low capital intensity.

[https://www.youtube.com/watch?v=j-qUaO- xzrY](https://www.youtube.com/watch?v=j-qUaO-xzrY)

<comment><USER29> Lots of omitted details there. A kite can pull its tether from one location to another location of lower potential energy, but how does it get back to the higher-energy location? If we're talking about a circular train on a circular track, half of the kites must continually have either a lower-drag configuration or a lower-wind altitude. That's plausible, but that's a lot of additional mechanisms, plus a lot of "cancelled-out" wind traction, plus a lot of friction as the train rolls around the track. Will there be power left over for electricity generation? Probably, but it isn't clear that it will be worth all the trouble. If a reasonable prototype exists, it should have been in the video.

</comment></comment></comment><comment><USER30> In the 1970s and 1980s there was much more variety in wind turbine design. There were two bladed machines, multi-blade ducted turbines, Darrieus rotors, and other exotic technologies. Outputs were in the 50KW range. Pacheco Pass in Northern California had examples of most of those. Some didn't work too well. Loss of blade accidents were common in the early days, with blades thrown considerable distances.

The three-bladed machines won out commercially. Machine size went up because output vs cost decreases with size, at least up to 1-2 MW. Lots of little machines were a pain to install and maintain.

Wind generators used to be AC generators synchronous to the grid. But with higher power semiconductors available, putting a big AC-DC-AC converter on the output to sync it to the grid is becoming popular.[1][2] This allows generating some power during low-wind conditions, and provides much more adaptability to wind gusts. When the wind speed changes, the blade pitch is adjusted to compensate, but on big turbines, this takes tens of seconds. Being able to adjust electrically in milliseconds avoids power grid transients.

The push for permanent magnet motors in wind turbines is more about converting to direct drive and getting rid of the gearbox. Wind turbine gearboxes are a huge pain, wearing badly for reasons that were only understood in the last few years.

[1] [http://www.theswitch.com/wind-power/](http://www.theswitch.com/wind- power/) [2] [http://new.abb.com/motors- generators/generators/generators-f...](http://new.abb.com/motors- generators/generators/generators-for-wind-turbines/doubly-fed-generators)

<comment><USER31> Pacheco Pass or Altamont Pass?

<comment><USER30> Right, Altamont Pass. The Veg-E-Matic for birds - a long, narrow valley filled with row after row of medium-sized wind turbines.

<comment><USER31> Indeed it is.

</comment></comment></comment></comment><comment><USER32> Relevant Low-Tech Magazine entries on wind-power, and small windmills:

 _Urban windmills harm the environment_ [0]

> A small windmill on your roof or in the garden is an attractive idea. > Unfortunately, micro wind turbines deliver hardly enough energy to power a > light bulb. Their financial payback time is much longer than their life > expectancy and in urban areas they will not even deliver as much energy as > was needed to produce them. Sad, but true.

 _Small windmills put to the test_ [1]

> A real-world test performed by the Dutch province of Zeeland (a very windy > place) confirms our earlier analysis that small windmills are a > fundamentally flawed technology

(Note that the picture shows that almost all windmills tested had three blades)

 _Wind powered factories: history (and future) of industrial windmills_ [2]

> In the 1930s and 1940s, decades after steam engines had made wind power > obsolete, Dutch researchers obstinately kept improving the – already very > sophisticated – traditional windmill. The results were spectacular, and > there is no doubt that today an army of ecogeeks could improve them even > further. Would it make sense to revive the industrial windmill and again > convert kinetic energy directly into mechanical energy?

Unlike this story, which certainly sounds interesting but shares no real data to back it up, Kris de Decker thoroughly digs through sources to write articles backed up by available data as best as possible.

[0] [http://www.lowtechmagazine.com/2008/09/urban- windmills.html](http://www.lowtechmagazine.com/2008/09/urban-windmills.html)

[1] [http://www.lowtechmagazine.com/2009/04/small-windmills- test-...](http://www.lowtechmagazine.com/2009/04/small-windmills-test- results.html)

[2] [http://www.lowtechmagazine.com/2009/10/history-of- industrial...](http://www.lowtechmagazine.com/2009/10/history-of-industrial- windmills.html)

</comment><comment><USER33> As a kid I always found it interesting that (some?) Spitfire had 4 blade propellors and the main adversary, the [Edit] Bf109 had 3 [1] and wondered, shouldn't there be an optimum?

[1] Not sure both changed the number of blades during WWII.

<comment><USER34> You mean Bf109 I think. The P-51 started 3 and then moved to 4. Ditto P-47. FW-190 and F6F stayed at 3 whole time afaik. Tempest started with 4. So it varied. But there is a trend of the early (1939) designs to have 3 and the late (1944) designs to have 4. I guess available power from the engine plays a big role, as engines got more powerful they started fitting 4 blades. Using the extra power on 3 blades would require longer blades (which is problematic), spinning them faster (again, problematic as tips reach sound barrier) or increasing the pitch (I guess there are aerodynamic limits for that).

<comment><USER35> This is a really cool write-up. Another thing that might be of interest was the performance of the aircraft. There's a guy in Texas with 6 non-flying 109s, a couple P-51s, and some other stuff for sale as a lot. He's a former stunt pilot, flew in the movie 'Battle of Britain' and several others.

In his words, the 109 handled much better at the limit than the P-51. The P-51 could dive and go very fast, but with poor control. In his opinion the 109 was the superior aircraft.

Not sure if it relates at all to the prop discussion, but maybe in the grand scheme of engineering? Those warbirds are fascinating pieces of hardware to me.

</comment></comment></comment><comment><USER36> You mean like one of these?

[http://www.windpowerninja.com/wp- content/uploads/2009/02/old...](http://www.windpowerninja.com/wp- content/uploads/2009/02/old_wind_turbines.jpg)

</comment><comment><USER37> Small turbines do exist. One was installed on This Old House recently: [http://www.thisoldhouse.com/toh/tv/ask- toh/video/0,,20961006...](http://www.thisoldhouse.com/toh/tv/ask- toh/video/0,,20961006,00.html) (jump to about 15:00)

But, it does have three blades.

</comment><comment><USER38> I like the idea of wind turbines, but in practice I think PV is the way to go (long term). I realize that for now it's a blend of technologies, but PV doesn't kill millions of birds and bats. I grant you, it's better than burning coal, but still we can do better eventually.

<comment><USER19> House cats kill 1,000 times more birds than wind turbines. Even cell towers kill more. It's nonissue.

<comment><USER39> They won't kill the same kind of birds, though. For example, there's a new rule raising the number of bald eagles which can be killed by wind turbines to 4,200 per year. I'm guessing that house cats kill few bald eagles.

It may still be a nonissue, of course, but the comparison with cats doesn't tell the whole story.

<comment><USER19> Fair point, I was just responding to the idea that wind turbines would kill all the birds, which isn't realistic. As a percentage of the bird population, it's negligible.

I don't see any reason why bald eagles would be more likely to be killed by turbines than other species of birds. If only 0.01% of birds are killed by turbines, then they would only kill 1 bald eagle a year out of thousands.

Regardless, this is more of a reason to invent solutions for repelling birds from turbines. Maybe we could come up with noises or lights that repel them. Or drones, or a water cannon robot. But I'm not certain it's even an issue.

<comment><USER39> The current rule is something like 1,200/year. There are about 143,000 bald eagles in the US. The 4,200 number is set at a level which they think the species can sustain. I don't know why bald eagles would be more likely to be killed by turbines, but apparently they are:

[http://www.fws.gov/midwest/wind/wildlifeimpacts/index.html](http://www.fws.gov/midwest/wind/wildlifeimpacts/index.html)

"Not all bird species are equally vulnerable to wind turbines. Eagles appear to be particularly susceptible."

<comment><USER38> Not all birds fly the same way, in the same regions, at the same altitudes. Balds eagles tend to soar and hunt in places we like to put wind turbines. Small birds tend to move smaller distances, often in about 100m around a water source.

</comment></comment></comment></comment></comment></comment><comment><USER7> There is a lot of bad information here, and it appears there are others in these who are also better informed than the author. Let me just hit up a couple of points that are fundamentally wrong, though.

\- "Conventional wisdom says wind farms should have their turbines placed in such a way that they don't interfere with each other, the fear being that placing one turbine too closely in the shadow of another will reduce the efficiency of the showed turbine." True, and this is why we have wake models based to predict the losses from other turbines and optimize placement.

\- "The rule of thumb, then, is that turbines be placed no closer than seven diameters apart. Keep that number in mind." Not true. You may find that a 7x7 array is relatively common in offshore applications, but a typical onshore application is more likely to be between 2-4 diameters apart in a row, with rows 7-13 diameters apart front to back.

\- "Oh, and turbines are placed seven diameters apart. That's it, no CFD." Wrong. But CFD is generally computationally complex, so we usually use models with reduced fluid dynamics equations to make it possible to iterate quickly. See previous comment about wake models.

\- "In some cases wind farm automation can cost as much as the turbines, themselves." I'd like to see these magical cases. A typical 2 MW turbine costs $2 million to purchase, and about $3-3.5 million total as part of an overall project of 50 turbines. SCADA is a minor fraction of this, as is operations.

\- "Shorter blades are stronger than longer blades, so the Lipps turbines can operate in faster winds." This is a non-issue. There are very few sites in the world that require even the highest wind speed turbine designs; most of the world is less windy, and the majority of sites benefit from using turbines designed for lower winds.

\- "Use permanent magnet generators and the turbines could be allowed to run 24/7 in any wind with no computer control required at all, leading to more production at even lower cost." Computer control of turbines is a non-issue, and the cost is minimal relative to the raw materials cost of the machines.

\- "This is because they use alternators that consumer electrical power to energize their windings so there is no point in turning-on the alternator (energizing those windings) until there's enough wind to generate a net positive amount of electricity." This is only a little bit correct, and mostly not. Wind turbines by design generally need to be connected to the grid to run, but winding energization is not why they don't start generating until there is enough wind. Turbines are generally on all the time, and typically consume anywhere from 10 to 50 kW at idle. And I don't know why he's using the term "alternators" to describe the turbine generators. The most common generator type is a doubly-fed induction generator, but squirrel cage induction generators, permanent magnet generators, and synchronous generators are often used. Usually turbines are connected to the grid through power converters which allow them to run at various speeds while remaining electrically synchronized with the grid.

\- "Remember the diameters are smaller so instead of hundreds of turbines we're talking about thousands of turbines for the same wind farm. Imagine a field of mature dandelions." This is actually a problem. When you can get 100 MW with a 50% capacity factor by building 50 machines in one township in Nebraska, why would you want to build 1,000 machines instead? How is that less complex?

\- "Try breaking into the industrial wind power business without at least $1 billion in capital. It can't be done. The incumbent companies like it that way, too." Manufacturing is capital intensive. News at 11.

\- "Lipps wind farms could be closer to cities and therefore have lower transmission losses, further increasing power output." Wind farm placement is about where the wind resource is. It's an economic decision.

\- "The result of all this not starting and then stopping is that throughout the year an average workload of 23 percent is reached by inland wind farms, 28 percent for coastal farms and 43 for off-shore." I have to assume his "average workload" here (a term I've never heard in the industry) is equivalent to capacity factor, which is the ratio of actual energy produced to the maximum possible. Most new projects in the windy areas of the US have predicted capacity factors of greater than 40 percent. High wind losses are typically very low, and online time is typically very high.

\- "China will build the heck out of those smaller blades." China is also building the heck out of the larger blades. China has more wind capacity installed than any other nation.

\- "And no insane cows, either. Cattle can't be pastured under wind farms because the motion of the turbine blades and especially their sound drives cows crazy." Tell that to these cows [https://www.flickr.com/photos/ashcreekphoto/7793429362](https://www.flickr.com/photos/ashcreekphoto/7793429362) (did he even do an image search before posting that? I've built wind projects on cattle ranches.)

Why does this post use such an old, crappy US wind map? Why not the newer DOE wind maps available at [http://apps2.eere.energy.gov/wind/windexchange/wind_maps.asp](http://apps2.eere.energy.gov/wind/windexchange/wind_maps.asp)

I'm sure I could go on, but this is just a fundamentally misinformed article. It's trying to make an aerodynamic argument (which I am not qualified to judge) using a mess of bad or incorrect information.

<comment><USER40> Came here to point out that I live next to a dairy farm smack dab in the middle of about (100) 1.5MW turbines. Cows aren't particularly intelligent animals to begin with, but they certainly don't suffer from fainting spells just because they graze under a huge turbine.

Other (industrialish) things cows don't mind: \- Tractors \- Feed grinders \- Silage conveyors \- Automatic Milkers \- Being lifted to a horizontal position to have their hooves trimmed. \- Having their eggs artificially inseminated.

I was unsure about the credibility of Cringely on the topic of turbine blade count right up until I read this statement. Then I was sure about his credibility.

</comment></comment><comment><USER36> The 2016 tag is not really necessary; this was published today.

</comment><comment><USER41> "why... very often the turbines aren't turning at all?" Someone told me that demand varies and it's easier to shut down a windmill than a nuclear reactor.

</comment><comment><USER42> More blades and closer spacing between windmills optimizes power / land area. But what matters is power / capital cost.

<comment> mark-r He tried to touch on that - making the blades shorter but in greater quantity will drive efficiencies of scale in manufacturing and shipping. And smaller turbines lead to cheaper towers. Hard to know if he's right without crunching actual numbers though.

</comment></comment><comment><USER33> I'm interested in the results when Cringely builds his farm. For example support costs from thousands instead of hundreds of turbines. How many on one pole are best. Also building costs over time e.g. when costs go down due to robots planting poles etc. which favors farms with more poles above those with fewer poles.

</comment><comment><USER43> I don't know much about wind turbines and the behaviour of moving volumes of air with regard to airfoils but there's one point I picked off of the article.

If I were to put my money either in the most advanced big-farm wind high-tech or in something that is decentralized, mass-produced, and well-abused by all kinds of groups of people, it would be the latter.

The article mentions that one billion is not enough to enter the game. That surely excludes a lot of the smartest and brightest people who might come up with new innovations and the billion-scale investments also seek conservative returns, further culling new ideas.

</comment><comment><USER44> This comment on the post is pure gold!

 _Fascinating! It's not about asking questions, it's about asking the right questions! The first framing question is efficiency from blade to outlet, but it's really about effciency from capital markets to factory floor to farm to outlet._

That should become a mantra. It's about efficiency from capital markets to revenue per customer.

</comment><comment><USER45> I would have guessed that it's a trade-off between efficiency and mimizing public outrage in densely populated areas (yes, outside the US that can be an issue). Three blades, when the turbine is not working, block less from the view than a large number of blades (which converge towards giant white surfaces).

</comment><comment> at-fates-hands Here's a much better Wind Resource Map than the one in the article: [http://www.tindallcorp.com/site/user/images/USA_Wind_Map_for...](http://www.tindallcorp.com/site/user/images/USA_Wind_Map_for_Tindall_Transp_2.jpg)

<comment><USER7> [http://apps2.eere.energy.gov/wind/windexchange/wind_maps.asp](http://apps2.eere.energy.gov/wind/windexchange/wind_maps.asp) has this map plus state by state maps available for download as relatively high resolution PDFs.

</comment></comment><comment><USER46> The more worrying part of this is that you need 1H capital to even try to get into this business if all you do is build the monsters. So that means few competitors (or even one) which makes monopolist behavior and unimaginative thinking likely.

</comment><comment><USER47> It seems Steve Jobs was inspired by Socrates: [https://en.m.wikipedia.org/wiki/Socratic_method](https://en.m.wikipedia.org/wiki/Socratic_method)

</comment><comment><USER48> In some parts of the world they use 2 blades so they can lay down the system when the wind is too high (think tornado/hurricane season)

</comment><comment><USER49> The less number of blades - the higher efficiency, should be an odd number to avoid standing wave and symmetric too. Thus 3.

</comment><comment><USER50> Why can't the blades be staggered so they don't follow in each other's wake?

</comment><comment><USER51> this is one of the best articles i have read recently. I too am a big fan of always asking why and trying to buck the trend of "thats just the way it is".</comment>


Why do most microwaves have such a terrible user interface? - <AUTHOR> http://timandjeni.com/blog/why-do-most-microwaves-have-such-a-terrible-user-interface/ <comment><USER2> I wish the post had gone deeper trying to answer the question. I'm not sure what the answer is, but I think several factors contributed:

1\. Microwaves originally had analog dials. The first digital UIs were seen on fancier, high-end appliances. This made them a bit of a status symbol. Eventually, tech costs came down and everyone imitated the high-end UI.

2\. Almost nobody grows up wanting to design appliance UIs. They're considered boring.

3\. Removing features is _hard_. If you remove a feature used by 1% of your customers, and you have 10,000 customers, that's 100 angry people. They'll be much more vocal than the slightly happier 9900.

Amusingly, the cheapest microwaves are often the ones with the best interfaces. I spent $80 on something like this[1] years ago, and I like it more than any fancy microwave. This includes the model touted by the author. Having only one knob (time) is too minimalist. I hardly ever touch the power knob, but it's occasionally necessary.

1\. [http://image.haier.com/us/products/kitchen/microwaves/W02013...](http://image.haier.com/us/products/kitchen/microwaves/W020131114629227085989.png)

<comment><USER3> It's also about what you like in the store and what you like at home.

People got swayed by the iPhone 4 design in the store and bought it, then once they own it they covered it in cheap plastic to protect the glass.

The flat surface on the microwave looks great and sleek. The many functions makes the oven seem good and sophisticated. Who knows what magic this microwave does when you ask it to reheat a slice of pizza! Surely it must be better than the normal heating function! Let's get that.

Once you are home, all you want is to set the time and maybe change the power.

</comment></comment><comment><USER4> The "one knob, that's all there is" user interface that the author of this post hails as a breath of fresh air is certainly simpler than the 34-buttoned UI he criticizes, but anyone who's familiar with the intricacies of microwave cooking knows that just as important as the cooking time is the power level.

You know those cheesy leftovers that you ordinarily nuke for 2 minutes, and the cheesy portion ends up a gooey, steamy mess, while the rest of the dish is only slightly warm?

Try nuking it for 3 minutes, but set the power level to 60%. You'll be amazed at what a difference it makes!

P.S.: Could you imagine a Hacker News crowd-designed microwave? There'd be buttons for "Add 2^1 seconds," "Add 2^2 seconds," "Add 2^3 seconds" ...

<comment><USER5> You could push and turn to adjust power.

<comment><USER6> Or have 2 knobs (Power and Time).

I used to have one like that many moons ago. It also had a start button and a stop/open door button. That was perfect.

<comment><USER7> Most toaster ovens have three knobs: temperature, time, and a series of what sound like discrete settings (bake, toast, broil, etc.) but are actually a graduated spectrum for heat distribution to the top vs. bottom heating coil. Pretty much a perfect UX (though you could toss out the heat-distribution names), and makes me wish that everything else—actual ovens, actual toasters, and microwaves—shared it.

</comment></comment></comment></comment><comment><USER8> The flat, non tactile buttons make cleaning much easier, a big plus in my book.

Commercial microwaves typically only have a few buttons as well:

[http://www.webstaurantstore.com/solwave-mw1000t-stainless- st...](http://www.webstaurantstore.com/solwave-mw1000t-stainless-steel- commercial-microwave-with-push-button-controls-120v-1000w/180MW1000T.html)

</comment><comment><USER9> Funny to find that someone submitted this two-year-old post of mine here. Sorry I didn't actually answer the question, heh.

Thanks for the insightful comments, all.

</comment><comment><USER10> I've actually got that same Panasonic in my office, and really appreciate the "Sensor Reheat" feature.

My meals have widely varying thermal capacities (chili vs a sandwich) so it's nice to have a single button to hit, to get my food uniformly hot every single time.

<comment><USER6> Does it also deal with uneven heating? Test with a few papadums[1]... :)

[1] [http://www.evilmadscientist.com/2011/microwave-oven- diagnost...](http://www.evilmadscientist.com/2011/microwave-oven-diagnostics- with-indian-snack-food/)

<comment><USER10> No. It only has a rotating plate, so I suspect it's not particularly evenly distributed.

When I said "uniformly" I meant that each meal ends up at more or less the same, "pleasantly hot" temperature as the previous meal, irrespective of their thermal mass, because the sensor reheat runs longer or shorter for the respective meals.

Works well enough for leftovers at work ;)

</comment></comment></comment><comment><USER11> My ideal would be two knobs and an illuminated push button.

The push button is "mute", illuminated when mute is enabled.

One knob is the standard toaster-oven style "twist to desired time", the other a power level knob (with minimum being a special for defrost).

Unfortunately, it's not going to happen, and for a very simple reason: cost. It costs less to do those stupid little membrane switches than discrete knobs / buttons.

My "good enough" would be separate 1s / 5s / 15s / 1m / 5m buttons. Where you press the button, it adds the time. Like how some timers work. And a dedicated mute button, and easy indication of if you are muted.

</comment><comment><USER12> I like the two knobs UI, it can be as simple as the single knob but it's more versatile. However, those can be annoying when you forget to turn the power knob the right way. A possible solution would be a led with different colors for each power level, that should avoid nearly all mistakes.

On a side note, my UI Design professor gave the microwaves as an example of a frequently bad UI. He had a theory for this: that customers also preferred more features. As in, when buying a microwaves, it could be tempting to choose one with 10~15 over one with 2 or 3.

That was just a theory, though - no studies whatsoever involved. I have never shopped for domestic appliances myself, so I don't know what I'd be tempted to buy.

</comment><comment><USER13> I had a microwave in college that I bought used for $10. It had a single knob that you could twist to have it run from 0-10 minutes. It was pretty much perfect. I don't ever use a microwave for anything besides reheating leftovers or melting butter.

</comment><comment><USER14> I was really hoping for an answer!

<comment><USER15> Most likely because an engineer designs it, or it's designed by committee. Let's see, how can we sell this same microwave that cost us $30 to make, for twice the money? Oh let's add "features" such as a 'popcorn button' that makes popcorn, or a 'defrost tbone steak' that perfectly defrosts...

etc etc, That said, the inverter technology in the panasonics are worth paying for... not to mention that they do have tactile buttons and a knob... [http://www.cnet.com/pictures/panasonics-nn- sd997s-microwave-...](http://www.cnet.com/pictures/panasonics-nn- sd997s-microwave-uses-inverter-technology-pictures/2/)

</comment></comment><comment><USER16> Probably for the same reason your TV/car/washer-dryer/digital watch/whatever is ugly and overloaded with "features" you never use: they cost nothing to tack on, and people will pay more for it.

</comment><comment><USER5> The major complaint I have with my current microwave is that when it's done it gives a simple two or three tone beep and that's it. You can't hear it outside the kitchen and it doesn't repeat.

<comment><USER17> The major complaint I have with my current microwave is that it _does_ repeat, since my apartment is small enough that I can hear it regardless of where I am, and there's usually a reason other than me forgetting if the food is still there after a minute.

I wish that sort of thing was made more prominent on the packaging.</comment></comment>


Show HN: Building a Meditation Controlled Orb - <AUTHOR> http://www.kpkaiser.com/entrepreneurship/building-a-meditation-controlled-orb/

<comment><USER2> I'd love to see more meditations and brain wave sensors dded to devices like basis.. I have been using the heartmath device and it works very well.....just need it integrated into my other data....

</comment><comment><USER2> heartmath device is cool too..would love to see meditative and drain wave measurements added to the basis device

</comment><comment><USER3> This is so cool, do want.

</comment><comment><USER4> Wow!! Great job on this!</comment>


Amazon Bans Sale of Apple and Google Streaming Devices - <AUTHOR> http://www.forbes.com/sites/ryanmac/2015/10/01/amazon-becomes-the-not-quite-everything-store-as-it-bans-sale-of-apple-and-google-streaming-devices/?utm_campaign=ForbesTech&utm_source=TWITTER&utm_medium=social&utm_channel=Technology&linkId=17528522 <comment><USER2> This is the beginning of a new stage of fierce competition. It makes business sense, but I can see growing lack of inter-operability between systems and devices. Bad for consumers.</comment>


Ask HN: What matters for getting back-end positions? - <AUTHOR>
 I've had many interviews throughout the years with many fails/passes. What I noticed is that the only thing that matters is how you do on the tech part, which is usually a Hackerank style question. It seems that how you approach/solve that question is about 90% of the interview and everything such as experiene/hr part/personal projects barely matter. The question is does having a good git portfolio of projects or personal website or overall experience matter/helps you get interviews/jobs or is it only like 1% improvement? <comment><USER2> _What I noticed is that the only thing that matters is how you do on the tech part..._

Tech skills are obviously important, but whenever I've interviewed people the "candidate is not a psycho" checks are equally, if not more, important. You can be the most technically skilled person in the world but you're probably in a list of candidates who can all do the job, so that's rarely a major differentiator once you're actually at the interview stage. Conversely, if you don't seem to be a nice person who I'd be happy to have in my team you're not getting hired.

Consequently a personal website or a portfolio that shows off the fact you're actually a decent person is really useful. Mentioning things like hobbies or volunteering gives the interviewer a great starting point to find out more about your personality - that's what makes a lot of people shine in my opinion.

</comment><comment><USER3> Experience and personal projects get you past the screening process, interviews get you past the hiring process.

Most companies aren't looking for personalized interview processes in order to assess a candidate's fit. They're looking for standard, comparable interview processes where they can justify their decision and hold interviewers accountable. It's easy to compare two Hackerrank scores, harder to (objectively) compare personal projects.

Hackerrank-style interviews suck and they aren't representative (not even remotely) of real working conditions. But they are good at something: evaluating the tenacity and the drive of a candidate. You need to work hard to ace these interviews, and companies are looking for candidates who are persistent and able to work hard—even on things they don't choose to work on.

<comment><AUTHOR> Do you think there is even point wasting time on personal projects for passing the screening process when in most cases it's a phone call and based on that I pass or fail the initial screening?

<comment><USER3> Realistically? No. But with the right personal projects you can impress the right people from your network and get a fast pass to onsite interviews.

</comment></comment></comment><comment><USER4> Afaik (not a personaler, I'm a consultant mostly working backend-jobs): experience is important, personal website/git portfolio is not, at all. Recruiters are not techies, they can't be arsed going through your github, and if they did, they wouldn't understand a thing.

Once you get invited, you need to perform vis a vis; if you don't get invited, you didn't meet the criteria.

The criteria vary by employer and position, but are mostly:

* is your code good enough?

* are you someone the team can work with?

When you get declined, ask for specific feedback. What went wrong? What can you improve on? Etc.

<comment><AUTHOR> This sounds fair, but in most cases recruiters treat you as just another potential resource. Even when I ask they never send a feedback and if I don't pass the interview they never even call/email. So usually it's me analysing or trying to guess what went wrong after I haven't heard from them in a while and realise I hadn't got it.</comment></comment>


Is Government or Industry Responsible for the Cable ISP Situation? - <AUTHOR> http://www.danielmiessler.com/blog/government-industry-responsible-cable-isp-situation

<comment><USER2> > Countries that have extremely fast, cheap, and accessible Internet have made > it a national priority to do so. They don't listen to companies who think > they can make more money by keeping speeds down and prices up.

I think it has to do more with the modern world building up their infrastructure much later than the United States did. Late to the game, in this case, isn't bad since you'd be using newer technology. The United States (government and corporations) that built the infrastructure years ago don't have a reason to upgrade. People are forced to continue using it.

> Who's fault is the current lack of competition?

Government. Businesses have only one reason for existing - maximize profits. They will do anything to do so, which is great! But the problem is the "anything" portion.

I've come to the conclusion that, unfortunately, government regulation is necessary. For example, look at China and their lack of pollution regulation. Cities in the US might have got to that point if it weren't for regulations (in the 70s?).

Another problem that isn't covered in this article is the, generally, uncaring public but that is a rant for another time, I think.

>It's cognitive dissonance at full strength. I feel you.</comment>


Review my new site : 48ers - Realtime Social Search - <AUTHOR> http://48ers.com

<comment><AUTHOR> Hacker News is my favourite site on the internet and having been a member for almost 4 years I've learnt a lot from everyone here. My co-founders and I couldn't think of a better place to launch our new site and get valuable feedback from a group of people we respect.

48ers allows realtime searching of a number of social networks - we created the site to scratch our own itch - to track what people are saying about other websites we own. We hope it might be useful for brands too.

Feel free to give it a go at <http://www.48ers.com> or jump straight into a search:

<http://48ers.com/search/?q=hacker+news>

<http://48ers.com/search/?q=airbnb>

<http://48ers.com/search/?q=balsamiq>

<http://48ers.com/search/?q=mark+zuckerberg>

Please comment here and tell us about:

* What you like

* What you dislike

* Any bugs you find

* Where you'd like to see this go in future (we have some ideas but would love to hear yours)

</comment><comment><USER3> I'm working on something similar with www.unscatter.com, though you and I are taking different approaches on clutter vs providing more context.

Likes: \- Layout and design. I wish I had a better knack for that kind of thing. 48ers is a lot of what I was going for and still haven't reached as for a minimalistic approach that's also appealing the to eye. \- The "Getting results" javascript is a real nice usability touch. Nice enough that honestly, would you mind if I implemented something similar when I get back to working on my own site? I prefer not to blatantly steal :)

Suggestions: \- It's a little slow. Not sure what your backend is, hopefully you're using something that allows you to submit all your requests at once and handle each as a callback. If you are, I would suggest benchmarking your requests to figure out which are your slowest ones and making sure you make those first. I shaved 10-30ms per uncached request by making my request to Facebook the first request I launched rather than the last, as it was the slowest API to respond.

\- Are you caching results? I did a search for "Epic 4g" (as I want to know when it will be coming out) and then immediately hit search again and it took a bit for that next request to load. I would really suggest you cache at least the data (as I'm doing) if not the entire results page (as I will probably move to with nginx caching modules) for x seconds/minutes and it will save you bandwidth costs, especially for those trending topics which may get a lot of concurrent hits if you app ever scales to appreciable traffic.

Only question I really have is do you have a plan for advertising other than Adsense? Adsense is going to have a hard time matching ads for search result pages.

<comment><AUTHOR> Thanks for taking time out to comment.

As you say Unscatter seems a similar idea and we can see where you're coming from re: context.

We hear you on the speed - this is what we are trying to focus on - make this a super quick, great user experience. You're right in that caching is the way to go - again it's one of those release early and iterate items. We don't presently do any caching as such so this is no doubt something we will iterate on.

In terms of monetisation - for the first few months we are looking at adsense to get a feel for how contextual the ads are and what the relative click through rates will be. After this we have some ideas that we hope will work out well.

</comment></comment><comment><USER4> Can you explain a bit more about how you actually get this data in real time? Are you scrapping these sites? Doing REST calls every x seconds. Or using the streaming API for twitter?

Are you storing any of this data persistently? Can I do historic searches on any term, or just something that was indexed before?

Are you planning on adding any sentiment analysis? Or any other analytics on the data, assuming you are storing it.

Do you have an API or plan to support an API down the road. What's your monetization plan?

<comment><AUTHOR> Presently we are using the various API's that are available for each of the services that we are linking into. We have some custom code which interogates this data and renders it to the user. In respect of historic searches and storing of the data, storing data is not something we are doing from day 1, however this is something we are certainly looking longer term. In terms of historic searches - again day 1, we search back as long as the various API's allow.

Sentiment Analysis is something we looked at, however at the moment we wanted to keep things stripped back - that's not to say we may not offer this in future as an advanced search feature or even a feature that users can turn on/off.

API's are on the agenda and these are actively being developed to allow others to call into the service. In terms of monetisation we are starting out with a contextual ad model (using Google Adsense to start) - which obviously hasn't worked out too bad for Google, however longer term we have some other ideas around this.

</comment></comment><comment><USER5> I'm not sure what this does differently from every other search engine, or search engine aggregator?

Aggregating results via third party APIs is a neat, although old, stunt -- but doesn't exactly translate into a startup business to compete with search engines.

<comment><AUTHOR> Our aim was to provide something that was uncluttered, simple and fast which (eventually) covers as many social network and real people's views of either what people are saying about your brand or whatever you wish to search on in realtime.

We ourselves use this daily as a tool to track what people are saying about our other web properties.

</comment></comment><comment><USER6> If I search for a hash tag I would prefer to only get stuff that actually has that hash tag in it. For example, searching for #mac return lots of tweets about mac and cheese, which isn't all that useful.

<comment><AUTHOR> Yep - we agree - we'll have a look into this

</comment></comment><comment><USER7> Have you considered adding RSS feeds on the search result pages, or would this not fit in with your eventual business model? It would certainly make me use the service at any rate.

<comment><AUTHOR> It's funny you should say that - this is a feature that is high on the to be developed list. We are trying to take the release, iterate often approach - <USER2> hopefully this feature will be in soon. Thanks for the comment - any other suggestions ?

</comment></comment><comment><USER8> I would refine the phrase "social search." To me, it means searching alongside other people with similar goals, rather than an all-in-one site for social media search.

<comment><AUTHOR> It is our intention to be an all-in-one social media search. If 'social search' does not portray this have you any thoughts on what a good tagline would be to meet our aim - any suggestions more than welcome. Thanks

</comment></comment><comment><USER9> Can you enlighten me on how you plan to differentiate yourselves from the existing real-time search engines like collecta, oneriot, etc.?

<comment><AUTHOR> Thanks for taking time out to comment.

Collecta albeit a good service we felt was a little cluttered and on occasion a little sluggish - our service's aim is to be decluttered, simple, fast social search. With regards OneRiot - they are more of a full featured offering where we intend to focus more on the core search function presented back to users in an uncluttered easy to read manner.

</comment></comment><comment><USER10> [Removed in the interest of responsible disclosure]

<comment><AUTHOR> Thanks - we'll take a look into that</comment></comment>


Tell HN NYC: Hackers & Founders Meetup #4 at Stand Burger (8/27 at 6PM) - <AUTHOR> http://anyvite.com/events/home/mv5fkn1a2j <comment><USER2> Is it possible to send out a note about these things a week or two in advance of the meetup? Each time I find myself wanting to go but being kind of busy but with more advance notice I would be able to make time. It likely does not matter at this point for me- I am in Paris at the moment and I am moving to the west coast in September :-/ ...but maybe this will help other people that would like to attend.

<comment><AUTHOR> As Cald mentioned below, we hold the meetups the last Thursday of the month.

<comment><USER2> my mistake. i guess i should have put this in my calendar. well i hope things keep going well for you all. wish i could have attended.

</comment></comment></comment><comment><USER3> I may skip Digital DUMBO this week to make it. I have one question though: What is the Hackers & Founders Meetup like?

      - Are there presentations?
      - Are people generally social?
      - Is it more than a networking event?

I'm on the nyyc list, but it's so low traffic that I haven't found any answers to these types of questions.

<comment><USER4> \- There are currently no presentations. There have been discussions about adding them in the future (right Dave?).

\- Everyone is very social. There are usually circles of conversations going and people bounce around between them. I have never encountered anyone unfriendly. I usually meet 10-20 people and have worthwhile conversations with 4-8.

\- At its core its a networking event. From it, I have personally made new friends that I collaborate with and hang out with on a pretty regular basis now. I have also started a project with a guy I met there. It really depends what you want to take away from it.

Is there something specific you are looking for, or types of people you want to meet? There is a pretty solid group of regulars that could help point you in the right direction. Its definitely worth checking out...

<comment><AUTHOR> That's right Adam. I think we can set something up for "lightning" presentations for next month, if we can get determine the right space here in the city.

I'll echo everything you said above: this is our fourth meetup under the name and I've been impressed each time with the turnout (we started small at 20 or so people and last month we had about 70 people show up over the course of two hours, which ended going into three of four if I remember correctly). The types of people you'll meet - other hackers, founders and those who are thinking about startups in general - is quite different from any other tech meetup here in NYC, from NY Tech, to Digital DUMBO, etc.

At it's core, we're about connecting with other hackers and founders who are passionate about startups (and the industry around it) while leveraging each other with ideas, help and support.

If you're interested in learning more, don't hesitate to reach out: daveambrose at googlemail dot com.

</comment></comment></comment><comment><USER5> I'd like to go (central Jersey is kind of dead as far as startups go), but it's quite a commute for after work on a Thursday evening. Any chance of doing these on Fridays or Saturdays in the future? You might get people from the region that you normally wouldn't get on a weekday.

<comment><AUTHOR> Where in central NJ are you? I'm from Hunterdon County and go back every now and then.

</comment></comment><comment><USER6> Is anyone else going to be a first timer besides me?

<comment><USER7> I think I'll be there. I just joined up a few days ago, but this could be fun.</comment></comment>


My name is not a URL  - <AUTHOR> http://factoryjoe.com/blog/2009/03/21/my-name-is-not-a-url/ <comment><USER2> Great article. One thing to point out is that iChat allows you to integrate with your Address Book, so that if you _want_ you're able to set things up to use real names when you're talking. It makes vcards that much more useful.

</comment><comment><USER3> URL-names just hit me as the breakthrough of Twitter, actually. I hadn't understood the power of Twitter at all until the other day I was reading a blog where the author referred to someone as @handle. My name is not unique: but, if we had a service that got enough adoption that gave everyone a globally unique string identifier, you could unambiguously reference real people across any medium. That's really powerful, and I think it's just starting to dawn on us the different ways we could use that. I still don't see an obvious monetization strategy; but people said the same thing about Google in 2000, so I don't want to be one to talk on that.

<comment><USER4> so like an email?

<comment><USER3> Yes but easier to control access. You don't usually want to give out your email address as a form of general ID, and there are all kinds of clever email-hiding methods used to keep from being crawled by spammers (i.e., foo at bar dot com or foo at google's email service). And @handle just seems more manageable (and more global) than firstname.lastname@example.com

<comment><USER5> More global? I might be misunderstanding you but email is everywhere. It's one of the things that is recognisable by your parents, maybe even grandparents. Wouldn't it be simpler, instead of trying to build out @handle usage, to add more control to emails? Everyone has one, they're much more open since only twitter (I think) has @handle things, and much much much more accessible (and global). Gmail has fantastic filters already, a bit of a pain to set up but they work. Wouldn't an improvement on those be better?

<comment><USER3> By more global I just meant that @foo would effectively put everyone under the same domain. Email just feels more fragmented.

Edit: also email puts restrictions on your identity. You're foo at some domain. @foo lets you pick a unique name that's valid online once you're old enough to pick who you want to be, without the footnote of _domain_ attached. Sort of how we all recognize Paul Graham as "pg", which fits his style.

<comment><USER6> > Email just feels more fragmented.

...which is good. I want to be able to choose who I trust with my ID-related information.

</comment></comment></comment></comment></comment></comment><comment><USER7> Interesting article but it's been a while since I've so strongly disagreed with everything someone sensible has written down in such a delightful manner ;-)

Just to pick two examples:

 _success will find the designer who most nearly replicates the world offline online_

No way! Microsoft Bob, anyone? Dragging offline metaphors online _can_ work but it fails more often than it succeeds (it even goes deeper than that - think of those who replicate desktop interfaces on the Web.. eugh!). The online world is a new one, not one that should mirror the offline world. Heck, even the newspaper industry is finally waking up to that one..

And with regards to Twitter URLs vs Facebook URLs, etc, I can use my Twitter URL as a URL in all my OTHER social networking sites, on my business cards, in my e-mails, etc.. but Facebook? I need a URL to be able to do that. Further, I'll often use URLs as a direct scheme to find things I want.. example I _know_ that I'll find some interesting Python stuff if I go to: <http://del.icio.us/popular/python> .. or how about interesting "news"? <http://del.icio.us/popular/news> .. these sorts of schemes are a big win whether it's for people's handles, general tags, or whatever.

</comment><comment><USER8> Seems like all these arguments are stemming from the (newly resurfaced) debate about "online personal brand", and creating an identity as such. I'm all for diluting these namespaces with GUIDs or similar--who's to say I'm the most important Joe Smith in the world?

<comment><USER9> "Online Personal Brand" is certainly something I've considered - it's why I've never cultivated a handle and just register as 'Jacob Aldridge' (or as close as User ID formats allow) wherever I go.

There's the fear that this involves one part of my life (say, work) with another (say, a weird fan film I did when I was at uni), but I actually enjoy combining them - my business clients enjoy knowing about my Guinness World Record, HN etc.

Five years ago it was much easier for me - probably 80% of the ego surf for my name was me. There's been a glut of Jacob Aldridges reaching their teenage years (and therefore Facebook, media etc) since then - much more diluted Google / Brand results.

</comment></comment><comment><USER10> Actually, I don't mind my name being a URL at all. My first name's Chirag and my site is <http://chir.ag> and I wouldn't mind getting facebook.com/chirag either. Where's the option on Facebook where I can set that up?

<comment><USER11> Pay $50k.</comment></comment>


Dhh: I would fail to write bubble sort on a whiteboard - <AUTHOR> https://twitter.com/dhh/status/834146806594433025 <comment><USER2> There seems to be a growing and vocal subgroup of programmers who think solving algorithm problems is about memorization. That worries me. Don't they understand that problems can be solved by thinking? That they're being asked about the most timeless and beautiful parts of programming, which don't depend on the technology of the day, and whose beauty is that you _can_ figure out everything from scratch? Or that solving such problems gave us computers and the internet in the first place?

...I must be getting old. I have nothing but ugly things to say about that attitude. Sorry, HN.

<comment><USER3> Unless you specifically work in a scientific environment, when do you ever solve problems using a novel, non trivial algorithm designed by yourself? An amazing amount of programmers are simply doing CRUD, batch processing, and mapping data from one format to another. It's not rocket science.

I'd bet that ~99% of programmers never created a new algorithm, or needed to. And that's fine. (where by new algorithm I mean an actual, unique solution lowering the bounds on some operation which is usually done in a simpler way) Outside of what's happening in ML research, I can't even think of recent known examples.

</comment></comment><comment><USER4> The first twitter response is pretty great IMO "Hopefully we won't get to the point where people take as much pride in ignorance about CS as they currently do about math."

Maybe you don't use bubble sort, but it is truly trivial and these arguments seem quite anti-intellectual.

<comment><USER5> I think the point is that memorizing bubble sort doesn't prove anything.

<comment><USER6> I might have trouble remembering the difference between bubble sort and, say, selection sort off the top of my head. On the other hand, I can implement insertion sort from scratch. It is so simple I do not need to remember the algorithm, I can just figure it out whenever I want.

I think there is a problem with the industry having forgotten the point of why we were asking questions like this in interviews in the first place. The question is not whether you can remember the algorithm, it's whether you can _implement_ such a simple algorithm in any programming language that both the interviewer and interviewee know.

Since the point is the implementation, not the memorization, even simpler algorithms than bubble sort might well make more sense. This is why we've got FizzBuzz for example.

As an alternative, the interviewer could take a moderately simple algorithm like say the Fisher-Yates shuffle algorithm, explain it to the interviewee on the whiteboard, and then see if they can implement it. But again, the point is not to test the interviewee's memorization skills. These algorithms are simple enough that any software engineer who can actually program should be able to implement them from a diagram and some textual/verbal explanation.

The question of coding on a whiteboard vs coding on the computer is a separate question.

<comment><USER7> Could you implement insertion sort from scratch at a whiteboard in less that 45 minutes? Including getting the partitioning part right? It's tricky, and at a whiteboard, it's particularly difficult to get right (well, for me it is).

If you can, well, hat's off. I'd have to study and be prepped for this. I probably could have done this in the past, but I don't walk around ready to take my algorithms and data structures final exam from 15 years ago. That's the thing I don't want to do anymore. I feel like I've taken that test enough times.

I'm pretty sure I'm all done with tech interviews. I'll look for some way to stay in the field that doesn't involve another 5 hours of whiteboard exams. There are other options. I'm aware that I have ruled out some possibly good opportunities, but I truly can not stand the idea of going through this all one. more. time.

If it were just bubble sort or even insertion sort, eh, that wouldn't be too hard. I've only interviewed at google once, but I felt the questions were far more complicated and difficult than simply implementing insertion sort, and as far as I can tell, you really are expected to make good progress and write a lot of code. That was the reason they give for the "no hire", that I hadn't made enough coding progress on the problems in the time allotted.

This is certainly their right (though I do get irritated when google lobbies congress to remedy the shortage of software developers, as if their recruiting and hiring process isn't part of why they're having trouble hiring!)

But me? Yeah, I'm out. No more whiteboard oral exams, no more uncompensated "take home projects". Done. If this were part of some sort of professional certification, widely recognized in the industry, that I could properly prepare for and take as a lasting, industry respected credential, then I'd do it. But no more tech exams or take homes at the whim of a potential employer. I've wasted enough time on this.

<comment><USER6> > _Could you implement insertion sort from scratch at a whiteboard in less > that 45 minutes? Including getting the partitioning part right? It 's > tricky, and at a whiteboard, it's particularly difficult to get right (well, > for me it is)._

I think you have confused _insertion sort_ with _quicksort_. Let me stress that not only would I have difficulty doing quicksort correctly in 45 minutes on a whiteboard, I'd have difficulty doing it in twice that time _on a computer_. And for exactly the reason that you specify -- the partitioning part of the algorithm is very hard to get right.

Insertion sort, on the other hand, is a breeze.

It might be reasonable to ask somebody to code the recursive part of quicksort assuming that they already had a function to do the partitioning part. This might be useful to see if they understand recursion.

<comment><USER6> > _But me? Yeah, I 'm out. No more whiteboard oral exams, no more > uncompensated "take home projects". Done. If this were part of some sort of > professional certification, widely recognized in the industry, that I could > properly prepare for and take as a lasting, industry respected credential, > then I'd do it. But no more tech exams or take homes at the whim of a > potential employer. I've wasted enough time on this._

I've never had a big gripe about whiteboard coding exercises, but I'm with you on the take home projects.

My big complaint right now is that it has become increasingly difficult to get through the first level of screening to even get _to_ a proper interview loop where someone could even ask me to code on a whiteboard.

</comment></comment></comment></comment></comment></comment><comment><USER8> I recently experienced this filter when I applied to one of the big tech companies without bothering to re-memorize my undergraduate-level algorithms. I figured having run two companies and fifteen years of industry experience with a dozen languages was good enough.

I didn't get an offer. But the filter worked: I wouldn't have been happy at a place that places value on the ability to memorize and regurgitate search results.

We just raised a seed round on the back of a deeply technical demo I wrote in my spare time.

</comment><comment><USER9> While I think the focus on knowing undergraduate level algorithms verbatim and gotcha riddles are silly and a waste of time, they're exaggerations of very useful techniques. Something like fizz buzz is simple enough and trips up a surprising number of people that were able to talk their way into the interview. Puzzles allow you to assess their critical thing skills without letting them get caught up in semantics that tends to happen if you make it about programming (too many questions about libraries, coding style, etc).

An immediate answer, even if correct, tells you nothing because it was something they memorized. I'm much more interested in how they assess and approach--I don't even care if they come up with an answer.

Completely unstructured interviews seem to be meandering and often you walk away with gaps in your assessment.

This approach is only really applicable to jobs where those skills are needed and isn't the whole interview.

</comment><comment><USER10> How many times in your career have you needed to implement bubble sort without the ability to google it? In my experience I can say never and imagine that's what other people would say too.

I don't think the point is that we should take pride in not knowing things so much as that perhaps this way of evaluating potential hires is not very good. Doesn't seem controversial to point out that doing a technical interview that tests skills not required on the actual job might not work well for finding the people you need.

<comment><USER11> I want to hire people that can write robust, maintainable software. Unfortunately, I do not know how to test for that. At my company we do not do algorithm quizzes because, for better or for worse, algorithm mastery is not really important for most of our work. We mainly talk about work experience in the interview.

</comment></comment><comment><USER12> While I don't think you should know how to implement bubble sort on the fly in an interview, you should probably understand what it is at a conversational level, along with merge sort and quick sort, especially if the position is senior or lead and requires a CS degree.

<comment><USER3> I think that's just a bad substitute for the real question: What's the big-O notation, how do algorithms differ based on the CPU / memory usage and existing data format. Nobody uses merge/quick sort as originally defined anyway. In reality it's going to be some mix of algorithms with a threshold.

So why not ask what you really mean by either asking the theory (big-O), or real world practice (you're adding a number to a large ordered data structure - how would you do that, what's the chosen structure, tradeoffs)

</comment></comment><comment><USER13> If you're hiring for "great", you need to realize it is a two way street.

As an employer, if you really think a white board quiz is the best way to see if you want to work with someone, ask the candidate to bring a couple of questions for the interviewer to solve, you know, so the candidate can tell if they want to work with you.

An interview is a _date_ \- you want to find out if you're compatible without coming off as a jerk.

That said, white board stuff never bothered me. I don't remember caring that much if I got the job and talking to other developers is kinda enjoyable.

</comment><comment><AUTHOR> Fwiw I think the emphasis on the ability to write code instead of ability to read and understand it has been given disproportionate importance when the reality is that we spend a lot of time (perhaps even more time) reading rather that than writing.

I blogged about this at length here: [http://lonetwin.github.io/blog/html/2016/07/01/code_reviews_...](http://lonetwin.github.io/blog/html/2016/07/01/code_reviews_instead_of_whiteboard_for_interviews.html)

</comment><comment><USER14> Does anyone agreeing with this tweet know what bubble sort is? It's fine if you don't but if it's explained to you it should be pretty trivial.

It's like saying "why should I have to write fizz buzz for an interview." Of course you'll never have to write it. You won't even have to use it.

I just need to know if you can write software _at all_ for this software developing job you applied for. Sure, we'll evaluate other, more important, things too.

<comment><USER14> Looks like this is related to [https://twitter.com/cyberomin/status/835888786462625792](https://twitter.com/cyberomin/status/835888786462625792), which is a _bit_ different. So nevermind.

</comment></comment><comment><USER15> they could just as well ask to do multiplication without a calculator. many programing languages already have a sorting function in its standard library.

</comment><comment><USER5> Agreed, the stupid quiz culture is getting old. I suspect people who cling to this tradition wouldn't be able to code their way out of a paper bag outside the sphere of well defined problems with canned solutions.

<comment><USER16> Or the hiring process is optimizing for "nerd culture", whereas most development is optimized for solving business problems, and the two are often at odds.

If the desire is for peers rather than coworkers, you might as well ask, "In which Marvel parallel universe did Wolverine have claws made out of banana peels instead of Adamantium?"</comment></comment>


Whatsapp profile picture lookup - <AUTHOR> http://whatsapp-pp.batuhan.org/ <comment><AUTHOR> hello, I'm trying to build a tool for fetching Whatsapp profile picture from number can you try it?

(feedbacks with your whatsapp privacy settings are appreciated)

<comment><USER2> Works very well. If you can put this behind an API I could be your first client ;)

<comment><AUTHOR> actually that's my goal. I will test this a little more and publish an api</comment></comment></comment>