Wikipedia:Reference desk/Archives/Science/2016 October 10

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October 10

What is this plant?

Please any one tell me Name of this creeper.

— Preceding unsigned comment added by Sameerdubey.sbp (talk • contribs) 04:19, 10 October 2016 (UTC)

I hope you don't mind I "thumbed" your very large images. Vespine (talk) 05:11, 10 October 2016 (UTC)

And I adjusted the layout. --69.159.61.230 (talk) 07:56, 10 October 2016 (UTC)

Removed duplicate Rojomoke (talk) 05:18, 10 October 2016 (UTC)

Plz tell me Name of this plant — Preceding unsigned comment added by Sameerdubey.sbp (talk • contribs) 09:24, 10 October 2016 (UTC)

Where in the world did you find it? When did you collect it? What type of area was it growing in? The answers to these questions can help. If you don't get an answer here, you might try at reddit's What's this plant. SemanticMantis (talk) 14:15, 10 October 2016 (UTC)

I'm pretty sure it's Dioscorea bulbifera, the Air potato. The same leaf shape and veins and flower bud arrangement can be found with a Google image search. -Modocc (talk) 14:18, 10 October 2016 (UTC)

Yes thanks its the same dioscorea.i found it in my garden.i found it in Orissa,india. Many thanks modocc — Preceding unsigned comment added by Sameerdubey.sbp (talk • contribs) 01:09, 11 October 2016 (UTC)

How long should a clock radio last on a UPS?

Our electricity was out for a long time because of hurricane Mathew. I have a clock radio that runs on A/C and it says that it uses 3 watts. I put it on a UPS rated at 780 watts or 1300 VA. The battery capacity is 187 volt-amp-hours. There is a chart saying that it should provide 300 watts for 20 minutes. Since the clock radio uses 3 watts, I was figuring that it would last 2000 minutes, or over 33 hours. There is a counter on the UPS showing how many minutes of life it has with the current load and that was showing less than 6 hours. The UPS was nearly fully charged when I started using the radio and it is new - I bought it this year. Why was it lasting so much less than my calculation? Bubba73 ^{You talkin' to me?} 07:39, 10 October 2016 (UTC)

The inverter will have its own power requirements, probably 5-10 watts, even if it is merely switched on and not powering anything. Greglocock (talk) 09:26, 10 October 2016 (UTC)

If the inverter uses on the high end of that 5-10 watts, that explains it. Bubba73 ^{You talkin' to me?} 15:26, 10 October 2016 (UTC)

The UPS manufacture should take into account the inverter drain and publish the available power deliverable. That said, the inverter is going to consume some linear power regardless of the drain (OK I know that not exactly right but talking base-load here) . Most UPS's are used for short brownouts and thus prolong longtime power outages may mess up the long-term calculations based on the manufactures data sheets.. This (I think) backs up the previous comment by Greglocock . The other thing to remember, is even if the UPS is fresh out of the box. Those storage batteries may not be able to hold their indicated charge. You could consider a cheap purchase (or steal, borrow, etc,) some wire wound resistors to act as a dump for the UPS's full rated power for the purpose of which it was advertised for. Should the UPS still fall short, then return it under warranty. --Aspro (talk) 12:10, 10 October 2016 (UTC)

A clock with a cord always seemed like a truly terrible idea. By comparison, the all too clever folks at ISIS use the Nokia 105, which is cheap enough to afford in the Third World and is alleged to be able to stand by for 35 days on a single charge, and includes an AM radio. Wnt (talk) 14:36, 10 October 2016 (UTC)

The OP may be referring to a much loved and cherished Clock Radio Alarm of a style like they don't make anymore. Sure, he could get a modern, boring, equivalent that cuts to battery upon a power failure and a RRC chip to ensure that if he goes camping (off mains 60Hz grid) it will still wake him up with an accuracy of a couple of milliseconds.. But that is not what the OP is asking.--Aspro (talk) 16:14, 10 October 2016 (UTC)

Well, the way ISIS customizes them, one of those cheap little cell phones can wake you up many blocks away. :) :( Wnt (talk) 10:34, 11 October 2016 (UTC)

Yes, the clock radio I have is one I've had for a long time. - probably since 1991. Bubba73 ^{You talkin' to me?} 16:58, 10 October 2016 (UTC)

Aw. That's assume. They just don't make them like that any more! The modern ones are of poor build quality and all made in China now. Think yours, may have one of the National Semiconductor MM5314N series of clock chips inside (all made in the US), so consider passing it on to a grandchild as a family heirloom.--Aspro (talk) 17:59, 10 October 2016 (UTC)

I don't know about the chips, but it is a Sony. I wish it had digital tuning. Bubba73 ^{You talkin' to me?} 19:36, 10 October 2016 (UTC)

Phase-locked loop digital tuning was only just being introduced at that time. My transceiver had it but is cost about £400 back then. Mind you my 1957 Pontiac Star Chief had a self-seeking radio. But there again, in bed, one doesn’t tend to move out of one local broadcast station area and into another. So there was no point in include this feature in a bed-side alarm clock. Also, even though it is a Sony, it still probably has this chip series as they were ubiquitous back then. They were duel standard. Outside North America, within a country with a 50 Hz main frequency one just shorted out pin 16 on the chip, on returning home, one simply broke the short. Unscrew the box and I bet, it has a MM5 n n n n n chip like one of these: [1] . Digital tuning … 60 years before, one had to fiddle for ages with the cat's whisker before even getting the chance to tune in. Oh, those were the halcyon days...--Aspro (talk) 21:07, 10 October 2016 (UTC)

I have two reasons for wanting digital tuning: (1) tune in more accurately to the station. Even though the one I have come on automatically is a local station, it isn't picked up very well in the house. I have to turn the radio a certain way to get it to come in at all. (It broadcasts with only 7,000 watts.) (2) during the power outage when stations were dropping off the air, I kept having to search for stations that were broadcasting information. It would have been a lot easier to find them if the tuner could scan. Bubba73 ^{You talkin' to me?} 02:56, 11 October 2016 (UTC)

See the problem. 7000 watts is actually quite strong and a external dipole aerial (even a cheap one that just tapes onto the wall above) works wonders for good reception. From memory though, I don't think these Sony Radios had any thing other than an internal ferrite rod. Not even a telescopic antenna. If it does, that’s easy, just hook the dipole aerial up-to that (unscrew it first and feed into the socket) . Failing that, the only other solution for a stronger signal would be to drill into the case and pass the the external aerial feed though. But at the minimum, you will need a capacitor or even a balun to match the arial to the radio. However, that dispenses with the need to turn the radio this way and that to get a strong signal. The other thing is: if your local station is broadcasting to mainly automobile audiences. The transmitters are probably vertically polarized. Domestics radios have their ferrite horizontal, so you might try standing it on edge for a stronger signal.--Aspro (talk) 13:57, 11 October 2016 (UTC)

The Sony clock radio has no external antenna and no screws for a dipole antenna. The station's transmitter is less than 10 miles away, but I can pick up stations 70 miles away better (probably a lot more powerful). We have a lot of electronic stuff in our house which may interfere with the reception. It is FM, BTW. Bubba73 ^{You talkin' to me?} 16:20, 11 October 2016 (UTC)

Are you thinking of the right phone? The article you linked to mentions use for making IEDs, but doesn't say anything about including an AM radio and a search also finds nothing. An AM radio is extremely rare in a mobile phone primarily I think because of antenna difficulties. By comparison FM radios are somewhat common in phones, both smart phones and classical phones, especially those targetting the developing market. Smart phones commonly rely on the earphone cord for the antenna as do some classical phones although some have a built in antenna that is sufficient. However I suspect the FM radio isn't a big selling point for IED makers. While nominally you could use that perhaps as a backup trigger AFAIK most simply rely on the mobile phone network for trigger. Nil Einne (talk) 03:08, 11 October 2016 (UTC)

BTW, the two fluorescent lights I tried on the UPS didn't work right, probably because that the output is a stepped approximation to the sine wave. Would an LED work on such a UPS? Bubba73 ^{You talkin' to me?} 15:33, 10 October 2016 (UTC)

USP's of the type referred to, are designed to power computers. Computers have smoothing capacitors in the internal power supply to smooth out spikes. So not surprised if your tubes “didn't work right”. If the tubes didn't work right, then it can be assumed that LED's (depending on their drivers) may also strobe. Solution: Place a electrolytic capacitor before the LED (or LED chain) and a resistor after.--Aspro (talk) 16:14, 10 October 2016 (UTC)

As the above, a UPS is really just to stop your computer suddenly and unexpectedly losing power (and data) during a power "interruption" or a brown out, it's not really a complete power "replacement" device. If you do have a full power outage, a UPS gives you enough time to startup a backup generator OR at least perform a graceful shutdown, it's not really designed to just keep running your computer "as normal". Vespine (talk) 22:22, 10 October 2016 (UTC)

Yes, I know, I've used them for years. I shut all of the computers down as soon as the power went out. I have five UPSs that I used for the radio and charging devices. We drained the three smallest ones. I used up about half of the battery on the largest one. Bubba73 ^{You talkin' to me?} 23:15, 10 October 2016 (UTC)

Is this your camping kit or did you actually have a blackout? Vespine (talk) 03:21, 11 October 2016 (UTC)

We were without electricity for 47 hours because of Hurricane Mathew (starting 6 hours before it hit). I was trying to keep the radio going to get news reports and get some lights. (I have a battery-powered radio with a telescoping antenna, but it would not turn on, even though the batteries are good.) Bubba73 ^{You talkin' to me?} 20:44, 11 October 2016 (UTC)

In most common installation scenarios UPS are intended to be used like that. However UPSes installed for alarms and home fibre connections are often intended to be used for most power failures and many people don't even have any provision for generators. (When it comes to home fibre connections, depending on the country I think many people don't even have UPSes.) However this is more commonly for the more routine (power cuts lasting several hours rather than those extremely rare events (at least in the developed world) lasting several days. Of course you commonly don't really need a UPS, a quick acting battery backup will do at least for the fibre system but it's often easier just to use a UPS of some times. (Alarms systems may not like any loss of power.) Ideally a DC to DC may be better, but some do use 240V UPSes. I believe some roadside telecommunications cabinet also rely on UPSes or battery backups (more commonly the former although sometimes a UPS may simply be called a battery backup even if it designed like a UPS) exclusively as they lack a connection for power to the telecommunications exchange and while it may be possible, it's generally fairly unlikely except in special circumstances that anyone is going to attach a generator to each cabinet. Nil Einne (talk) 03:35, 11 October 2016 (UTC)

• Sounds like its time to think out side the box. Depending on a UPS is like putting all ones eggs in one basket. Don't know what your financial situation is like but LED lanterns are inexpensive today and last for days. An auto battery with a inexpensive DC-to-DC converter bought from (say) eBay will keep a cheap (£4.00) Raspberry Pi (that can maintain internet connection) going for days and days, plus a cheap FM/MW transistor radio with a proper arial. The car battery will also (via the DC-to-DC converter) recharge your phone many times. Start preparing now and you will be prepared before Hurricane Nicole and Otto hits, (Otto hasn't got going yet but it may be coming your way when it does).--Aspro (talk) 23:39, 11 October 2016 (UTC)

As a user of the Raspberry Pi, I must question your advice that it can be powered for days and days from a car battery. The RPi draws (at 5 Volts) in the vicinity of 1 Amp, but usually not more, when idling or when doing tasks (it doesn't vary much). It's quite a power hog and not at all like microprocessor chips that draw milliamps. In 24 hours, continuous use would virtually flatten a fully charged car battery. If you mean that it could last days and days if turned on briefly to check emails every few hours and be switched off during the intervals, you should have said so. You also haven't mentioned how the car battery will power the associated monitor and keyboard, since they are peripherals that aren't part of the RPi package. Akld guy (talk) 20:35, 12 October 2016 (UTC)

Ah, you have obviously had the benefit of a high fluting education better than mine. Yet, in simple terms, in the ancient mathematics I was taught, a 70 amp-hours auto battery will power such a devise for at least 48 hours continuously, i.e., plural -days in normal use. But perhaps you expect to leave your TV and everything on 24/7, in which case -the reply is not applicable to you. One must credit the OP with having a bit of common-sense to understand what I meant and do a dry run before Otto hits. Nice to know your using a RP however.--Aspro (talk) 19:47, 13 October 2016 (UTC)

I don't like the sarcasm, and you still haven't answered how the car battery will power the associated monitor and keyboard which will draw far more than the RPi. Akld guy (talk) 23:38, 13 October 2016 (UTC)

Level (logarithmic quantity)

Level (logarithmic quantity)Abandera61 (talk) 10:01, 10 October 2016 (UTC)

According to me , and at first sight, Formulas in "Units of Level" are not correct.

For "root power" or "Field" quantities is:

Lf = ln( F / F(0)) , which means: ln( F / F(0))Np = 10*log(10)( F / F(0)) dB.

Not:

Lf = ln( F / F(0))Np = 2*log(10)( F / F(0))B = 20*log(10)( F / F(0))dB.

And for "Power" quantities is:

Lp = 1/2*ln( P / P(0)) , which means: ln( P / P(0))Np = 20*log(10)( P / P(0)) dB.

Not:

Lp = 1/2*ln( P / P(0))Np = log(10)( P / P(0)) B = 10*log(10)( P / P(0)) dB.

Want to know , if I can edit the page , after further checks, and if it can affect other articles automatically.

hope to have put "Abandera61 (talk) 10:01, 10 October 2016 (UTC)" in the right way, best regards alessandro

Article link: Level (logarithmic quantity) -- ToE 12:28, 10 October 2016 (UTC)

Reference: § 8.7 of Guide for the Use of the International System of Units (SI): The Metric System. -- ToE 13:12, 10 October 2016 (UTC)

Why do you think that the article is wrong? A power ratio expressed in decibels by definition is,

$L_{\mathrm {p} }=10\log \left({\frac {P}{P_{0}}}\right)\ \mathrm {dB}$

Voltage is a field quantity and power is proportional to the square of voltage, so

$L_{\mathrm {f} }=L_{\mathrm {p} }=10\log \left({\frac {P}{P_{0}}}\right)=10\log \left({\frac {V^{2}}{V_{0}^{2}}}\right)=20\log \left({\frac {V}{V_{0}}}\right)\mathrm {dB}$

assuming that impedances are the same for both voltages. SpinningSpark 13:41, 10 October 2016 (UTC)

Very Hidden in comparison to " Decibel" https://en.wiki.x.io/wiki/Decibel. Cross Checked and I have understood.

Thank You Alessandro Bandera Abandera61 (talk) 13:56, 10 October 2016 (UTC)

Do the sparks from car welding robots have any effect on the car or robot?

The robot presumably is tougher than thin car metal but drops of molten metal must keep freezing on the robot for years. Sagittarian Milky Way (talk) 18:16, 10 October 2016 (UTC)

Robots spot weld body shells, so no molten metal spilling all over the place. Not even sparks. Similar to blacksmith hammer welding. They just get dusted in iron oxide.--Aspro (talk) 20:13, 10 October 2016 (UTC)

No sparks? See Automotive Spot Welding production line. -- ToE 20:33, 10 October 2016 (UTC)

Note that sparks, having a high surface-area-to-volume ratio, cool quickly as they shoot through the air, so they are not molten when they land, they are solid. StuRat (talk) 21:17, 10 October 2016 (UTC)

I worked in a tool shop for a while that had a manual welding "production line" with several people using MIG welder pretty much all day. Those definitely DID constantly spit out little balls of metal, and yes there were little balls of metal everywhere, but they are so small and most of the time if they build up to more than one "layer" on anything (jig, frame, table, etc) they just brush off. I think very very rarely, someone would get a grinder out if some build up happened in an inconvenient place. Vespine (talk) 21:57, 10 October 2016 (UTC)

Spatter builds up, but doesn't fly all that far (it's dense). So anywhere exposed to it is usually covered by something non-metallic to which it won't stick. For wire-feed welding, spatter does build up around the gas shield nozzle and has to be cleaned off periodically. It can also be a problem around fume extraction vents (if the atmosphere is kept human-friendly), where the airflow can be enough to draw light spatter into it, where it accumulates.

Anti-spatter spray is an aerosol (usually a silicone) which can also be used to make surfaces non-adherent to spatter. Andy Dingley (talk) 22:18, 10 October 2016 (UTC)

You might find this interesting: http://www.loctite.com.au/aue/content_data/358535_Protective_coatings_for_welding_white_paper_Digital_Jul14.pdf - why a more robust solution than anti-spatter sprays is needed. Andy Dingley (talk) 23:48, 10 October 2016 (UTC)

Core

Does Uranus have a solid core? If so, what is it made from?--178.101.53.88 (talk) 23:35, 10 October 2016 (UTC)

According to our Uranus article, the planet has a "a rocky (silicate/iron–nickel) core in the centre". Someguy1221 (talk) 23:38, 10 October 2016 (UTC)

How is that inferred? We can say a body's mass is consistent with the presence of such a core, but it's also consistent with a bigger core of ice. Can its moment of inertia be measured? —Tamfang (talk) 00:41, 11 October 2016 (UTC)

I don't fully understand the math behind it, but many observations feed into the model. Specifically: surface spectroscopy, mass, radius, gravitational dipole moment, gravitational quadrupole moment, and modeling of the behavior of different materials under high temperature/pressure. As far as I can tell from reading papers on Uranus' core that I don't fully understand, you can't make a model agree with all of this without having a rocky core. Someguy1221 (talk) 00:57, 11 October 2016 (UTC)

Also I dare say evolution of the solar system might have a few things to say about what is likely and unlikely to be found at the center of a gas giant. I strongly suspect there are very good reasons why no one expects to find solid ice in the middle of any planet, let alone a gas giant. Vespine (talk) 03:06, 11 October 2016 (UTC)

Yes, there are reasons to think most planetary cores are primarily iron and nickel. Iron and nickel are the most common "heavy" elements in the universe because their nuclei are the most stable. Denser elements tend to sink to the center of a planet, so iron and nickel, along with any denser elements, "want" to sink to the core. --47.138.165.200 (talk) 10:34, 11 October 2016 (UTC)

But, Uranus is rather unique in that there is much evidence of a major collision in the early formation. It is further away than models show it should be. It is rotating on its side. It radiates almost no heat. That last one fits with a collision that would have kicked out most of the rocky or metallic core, leaving a sparse icy ball behind. The magnetic field, which was traditionally thought to be solely created by cores may not come from the core. It is off by about 60 degrees, but so is Neptune's. Therefore, the theory that it comes from movement in the core may be wrong. It may come from another source. In the end, our current models and expectations make us believe that Uranus has a rocky/metallic core. However, it is strange and as we learn more about it, we may very well discover that it has a core of loosely compressed ice. 209.149.113.4 (talk) 14:07, 11 October 2016 (UTC)

I don't see how you'd get a core of ice. The successful models of Uranus inner structure all assume a core density of ~10g/cc, which as far as I know is way higher than you could achieve with water/ammonia ice, even under extreme pressure. Someguy1221 (talk) 21:51, 11 October 2016 (UTC)

I would have loved to prove you wrong, but [2] says that you need pressures in the ballpark of 100 GPa (one million times the atmospheric pressure) to even reach 2g/cm^3 in water. So yeah, 10 sounds hard. Tigraan^{Click here to contact me} 08:05, 12 October 2016 (UTC)

The "we may very well" is used to indicate that the following statement is unlikely. However, it is used in this case because currently accepted models of the core of Uranus indicate that the inner core of rock/metal is very small and very cold. The outer core (mantle) is vary large made of ice. The interesting part isn't that it is made of ice. The really interesting part is that this ice exists in high pressure and high temperature (relatively - you have to note that Uranus is much colder than any of the other planets). So, the icy mantle of Uranus is a very unique and unexpected feature - if it actually exists. 209.149.113.4 (talk) 17:53, 12 October 2016 (UTC)