CaptainPanic

Well? I obviously don't have the same cable connection as you (I'm probably on a different continent), but I do share the same curiosity. How did they move those blocks? p.s. To answer the thread title: I'd use hovercraft technology. You'd need about 2 bar absolute pressure (1 bar overpressure) to lift such a block. That's a pressure that you might even achieve with a bellows. (A lot of them).

The sun is 8 light-minutes away. We only see anything that happens at the sun 8 minutes later. That would include the sun exploding - which is not the most likely event. It's commonly accepted that, unless something really weird happens, the sun will first grow to a red giant (and swallow the earth in the process), before it'll really explode in a supernova. that process will take thousands or millions of years. And it will happen billions of years from now. Gilded was talking about the sun exploding because some other event (for example aliens and their cursed SunBusterBombs blowing up our sun).

You can actually test this at home. It's a fun experiment, and it will make a lot of things wet around you: -Take a towel, and soak it in water. -Swing it rapidly around, and see if the towel is losing water or not. -If other things get wet, then it is probably safe to conclude that this water is coming from the towel. (Don't do this in the rain, you cannot observe the water!) -If other things got wet, you can conclude that the towel became a little drier.

Glad to be able to help. As some other forum member says in his signature, if you like my comments, click on the little scales symbol (add to reputation)

Hmm... yeah, if you don't know either the A (area) or the U (overall heat transfer coefficient), then you'll have to regard them as 1 parameter. What's a AHU? And what's a CAV? I love abbreviations, but I never know what they mean.

Well... the problem challenge that you have, as I said before, is that the energy contents (the energy that can be exchanged) is not equal on both sides. So there would already be 2 ways to define the efficiency (both sides of the heat exchanger). But regardless of that... Normally, a heat exchanger is designed to exactly match certain targets. You're kind of reverse-designing it. You have built a heat exchanger, tested it to see how much energy is being exchanged between 2 flows, and now you try to give it an efficiency. If I design a heat exchanger (for chemical industry) I specify the in and outgoing temperatures of a certain flow, and that exactly determines the heat exchanging surface that I need. Because the heat exchanger then does exactly what I want it to do, it's rather pointless to conclude that it's 100% efficient. So I leave that out In short, I never talk about heat exchanging efficiency. The parameters that are of interest to me are the heat transfer coefficient, and the heat exchanging surface (and of course the temperature difference). The flow of heat, Q is determined by those parameters: [math]Q = U\cdot{A\cdot{\Delta{T}}}[/math] [math]Q[/math] = heat flow (W = J/s) [math]U[/math] = overall heat transfer coefficient (W/m2K) [math]A[/math] = heat exchanging surface area (m2) [math]\Delta{T}[/math]=temperature difference (which is actually not constant) I failed to find the overall heat transfer coefficient for air-air atmospheric heat exchangers in my handbook (Perry's chemical engineers handbook). I guess that's because they don't exist (the heat exchangers themselves don't exist). p.s. I think this is engineering. At least, I studied engineering to learn this, and so does Mil75HK.

Chemistry is not abstract. You can touch it and feel it, even though it often hurts and it's not advisable in many ways... What I mean is: if you calculate the heat of a reaction (modeling, with textbook methods), and then you do it in the lab, then it will actually become warm or cold. It's not abstract.

Carbon will burn. If you have pure carbon in a powder form, it will burn. Sometimes you get a powder that also contains carbon (and other things), and it will not born. Why not? Simple: the triangle for creating fire: heat, fuel, oxygen. Oxygen and fuel (the carbon) are present, but the carbon concentration is so small that if it burns, it cannot heat up the rest of the material to keep burning. So, there is not enough heat. Slag is such a material that does contain some carbon, but really not enough to sustain a fire. It contains all kinds of other minerals that are already oxidized (metal oxides and other stuff).

The point I was trying to make is that National Geographic is mainstream media. The point still stands. Interested in attracting the masses. I thank SkepticLance for providing another source for the information, because New Scientist does have the disclaimer that a good study has: That's the difference between science and mainstream media. Peer reviews.

I'd express the efficiency in energy / energy (Joule/Joule). that is: the amount of joules that you exchanged related to the maximum. Please note that with cooling and condensation on one side, and only heating on the other side, you can exchange more Joules on one side of your heat exchanger than on the other (unless you plan on evaporating the condensed water again on the other side, which might not even be such a bad idea). If you give the efficiency, you'll have to explain what it means anyway. You can't get away with giving just a number. Have you considered looking up some formulas? http://en.wikipedia.org/wiki/Heat_transfer will give you a start. Disclaimer: formulas can get quite nasty. Eventually you'll also need the links I provided before. Actually, you can just check turbulence with some smoke. Although calculating is cool, measurements and observations are better. The equation for the dew point is still weird. Have a look at http://en.wikipedia.org/wiki/Vapor_pressure - which is, imho, the more common way to look at condensation and evaporation.

I'm afraid that this thread is related to all the HHO crap that you can find on the internet. But on topic again: The use of hydrogen should be seen in the same category as using a battery. You can charge and deplete a battery, but if you can connect anything directly to the net, then that's the way to go. Also, cars run on fuel. You can use hydrogen for that, but it is indeed made of fossil fuels. The only advantages of hydrogen in cars are: cleaner city centers (it's only a local effect, certainly not global) and perhaps innovation will go faster with a larger hydrogen-vehicle market.

Although I agree that what Flashman said sounds logical, I must say that there exist pressure waves that travel at speeds that are greater than the speed of sound... These occur for example when high explosives detonate. So it's more complicated than what Flashman proposed. Since I am no expert on the field myself, I will just recommend this wikipedia page, which shows a formula to calculate the speed of a P-wave as a function of modulus of incompressibility, μ is the modulus of rigidity and ρ the density (also with links to those 3 concepts).

In the company where I work, there are 3 unions that represent some of the people working here. The 3 unions and the board of directors are now negotiating money and other things. It all seems very civilized, and they act on behalf of all the workers here (and I am not a member of any of them). There exist some pretty large unions here. They have contact with the government to discuss what is reasonable to ask for the coming year. They always have such meeting in the fall. So it was not long ago, and the financial crisis had already started. I don't remember details, but the unions agreed with the government to take it easy this year. Just to show that unions don't have to be all bad. I really get the feeling that the system works here.

It depends. If you want hot air, it makes sense to heat the air directly. If you want hot water, it makes sense to heat the water directly (solar boiler). If you want electricity... well, you get it. I'd say that the general rule is: the more steps you put in between, the more efficiency losses you get.

Firstly, you mention that the relative humidity is 85% outside (where it's hot and humid), and that the air inside is 55% moist. That does not make any sense to me. You obviously cool the air coming in, which should cause condensation. Then the air coming in (at Tin = 25 deg C) should logically be 100% moist (saturated). the only way to get it below its saturation concentration is to cool it even lower, condensate even more water, and then heat it up again. But that would not make any sense (unless removing the moisture is your goal, rather than reducing the temperature). In addition, the goal of the whole thing is (I think) to cool the air coming in. In the heat exchanger, all your cool air is heated by condensation. So the hot air loses water, but not much heat. Condensation is a problem, but I don't think there is any solution that is also energy efficient. Finally, a gas-gas heat exchanger is always inefficient. And in addition to that, your temperature difference is only 8 degrees. There is sort of an engineering rule of thumb that you need at least 10 degrees difference for sort-of reasonable heat exchanging. It is possible to heat exchange anything, but the size of the required heat exchanger will go up. Do you have any fans to move the air? You want a turbulent flow of air in the heat exchanger. If you have a laminar flow, it's horribly inefficient. You can check this easily by calculating the Reynolds number. Finally, I have never seen a relation to calculate the dew point of water in air. I usually just use the vapor pressure (which can be found easily on internet or handbooks).

About the prediction that there will be an ice age: With 7 ice ages in the last 650,000 years, it is no rocket science to "predict" that there will be another one in the next 10,000-100,000 years. I also predict that the sun will go down and also come up in the next 12-36 hrs. About the prediction that it will be the most severe: That fits into National Geographic's standards (programs about super volcanoes, super storms etc). it just sells better. Also, in the article, the study leader of the team that made the model says: ""It's hard to say what's going to happen," after which the National Geographic ignores that, and opens with a screaming headline. It's just typical 2008 journalism. National Geographic is mainstream journalism, not science.

Or here, here, or here.

The only example of legalized (tolerated) sale of marijuana is the Netherlands. And luckily for this discussion yesterday's newspaper (Volkskrant) published some numbers on consumption of the groups 15-64 and 15-24. In both groups, the Netherlands is merely average. Article (in Dutch): http://www.volkskrant.nl/binnenland/article1094054.ece/Nederlanders_blowen_niet_massaal Picture:http://www.volkskrant.nl/template/ver2-0/components/thumbnail.jsp?id=132411 translation of country names in that link: Nederland = Netherlands Frankrijk = France Belgie = Belgium Verenigde Staten = United States Duitsland = Germany Italie = Italy Groot Brittanie = Great Brittain Spanje = Spain Left leaf is the average street price (of an certain quantity, probably a gram) Right leaf shows the most recent use of cannabis in the population, in %, for the mentioned age group. Having said that... On topic of reducing the deficit (of any government, not just the US): Decriminalizing marijuana means: "decrease spending, increase income". Decrease spending: -You'd need a lot less police (and army?) - that will save money. Increase income: -(Several million) People would be released from jail, and their records should be deleted. So they're free to get a job. Of course some of the lazy bums won't... but some will. They'll pay the normal income tax. -If people would buy marihuana, which is legalized, you can get healthy competition. Like with tobacco, you can grow it cheap, and you can tax it immensely, and nobody will really complain. Sadly, there is no country in the world that does this. Not even my own... although we're pretty close.

I think that banks have undergone a great innovation. You can use internet to do banking, and money can go around the earth faster than anything else. This has great potential. As an analogy with cars, I would say that innovation can be overdone (imagine a battery powered car that would become so popular that you'd need an additional coal powered plant on every street corner - not exactly desirable), and it can also go the wrong way. That does not automatically mean that the innovation itself is wrong. In fact, most technology and most innovation will have to re-invent itself a number of times. The concept of "bank" is not wrong. It's just wrong that we have no clue what the money represents anymore. This is a great argument against unions. Can I translate your argument as: "I ignore previous argumentation, and I want to to give me a decent argument!"? I think I just gave 4 points which are good about unions: You don't have to fight for a good pension yourself anymore - unions do that, and with success. you get healthcare (insurance) when you get an accident at work you get better safety you got not more child labour Do you honestly think that each individual labourer can achieve all these things by themselves? You need to unite a little to get that. Unions do that... in theory. Apparently unions in the USA are total crap. ... so where I wrote unions before, I mean "European unions".

I think that banks have undergone a great innovation. You can use internet to do banking, and money can go around the earth faster than anything else. This has great potential. As an analogy with cars, I would say that innovation can be overdone (imagine a battery powered car that would become so popular that you'd need an additional coal powered plant on every street corner - not exactly desirable), and it can also go the wrong way. That does not automatically mean that the innovation itself is wrong. In fact, most technology and most innovation will have to re-invent itself a number of times. The concept of "bank" is not wrong. It's just wrong that we have no clue what the money represents anymore. This is a great argument against unions. Can I translate your argument as: "I ignore previous argumentation, and I want to to give me a decent argument!"? I think I just gave 4 points which are good about unions: You don't have to fight for a good pension yourself anymore - unions do that, and with success. you get healthcare (insurance) when you get an accident at work you get better safety you got not more child labour Do you honestly think that each individual labourer can achieve all these things by themselves? You need to unite a little to get that. Unions do that... in theory. Apparently unions in the USA are total crap. ... so where I wrote unions before, I mean "European unions".

How on earth do the unions get the blame here? Perhaps you can enlighten us a little? In general the unions make sure that the vast majority gets paid a little better, and the tiny rich minority a little less. They're the only bit of socialism that make sure workers have a pension and such. It is absolutely true that companies would be more profitable if they could just dump you at the age of 65, in stead of paying you a pension. But... never mind. I'll never understand Americans. Blame your unions... tsk. You know that companies would also be more profitable if they could use child labour? If they wouldn't have to pay any insurances for the ill? Or if safety wasn't of any concern? Why don't you throw all that also overboard? Hell, workers conditions were so much better in the 1800's. Apologies for ranting some European (read: evil communist) thoughts.

Bark certainly contains lignin, which we already established when we said there is eugenol in the mixture. The cellulose is, imho, not likely to do much. There exists a process to treat woods called organosolv. Organosolv is a process where you add ethanol/water mixtures (i.e. vodka) to plant material. It normally goes at 100-200 deg C, and a residence time of minutes up to hours (don't know exactly, it's probably also wood-dependent). The lignin (which is a polymer of phenols and other stuff) and part of the hemicellulose (mostly C5 sugar polymers) will dissolve. The cellulose does not dissolve, which is why it is popular in the paper industry. So the gooey stuff is either the dissolved lignin with ethanol and water. But lignin is, in general, really sticky. Also, it should precipitate out again if you add water (dilute the ethanol). Perhaps you can try that for us: take a small sample, and dilute it with water. With diluting I mean "add at least twice the amount of water as there is ethanol present". (Before you do this, make sure that you don't include all the crap at the bottom of the flask - it should be sort of a clear solution). The longer I think about it, the less likely I think it is that you actually made such resin. Much more likely that you just dissolved, or partially depolymerized lignin.

Awesome! Those look really pretty! Congrats!

It's possible that the ethanol evaporated as was suggested before. For that you should try to remember how much there was before and after that 1 year of storage. If there is a significant difference, you lost some solvent (ethanol and possibly water). Another option is that the eugenol (which is a phenolic compound) has reacted with the aldehydes. This is a common reaction to produce resins. Such resins are commonly produced with synthetic phenol (from fossil origin) but are also of interest to the biomass-chemists because the phenolics are one of the few products that can be made from lignin (a plant polymer). The lignin degradation products contain also eugenol and a wide variety of other phenolics. Cinnamon also contains those. Cinnamon also contains Cinnamaldehyde, which could be the aldehyde you need for the resin-producing reaction. But unfortunately I cannot find much about the concentrations of those compounds present in the cinnamon, so it is hard to say if these are present in high enough concentrations to give a reaction of any significance... But a polymerization reaction definitely seems what happened, because of your description of the mucus. Polymer solutions also behave gooey like a gel, like you described, whereas concentrated sugar solutions will behave more like syrup (like a gel vs. sticky).

There are 2-and-a half ways: 1: The hydrogen that has lost an electron (but has not yet joined up with another molecule) is written as [ce]H+[/ce]. The + shows it's positively charged. So there's pretty little guessing here. It's just reading. 2: In case the hydrogen joined up with another molecule, you must count the electrons/protons. If there is a positive charge, then you can bet that some atoms lost an electron (why else would it have a positive charge?). 3: Acids -by definition- lose protons (they get rid of the positively charged hydrogen atom, keeping the electron). The fact that they do this makes them an acid. It is the definition of acid. Strong acids do it always, weak acids do it sometimes (and you will learn later to calculate exactly how much). So if you notice that you're dealing with an (amino)acid, then you just search until you find it.