CaptainPanic

I am not sure fiona agrees with you. The correct words are "flora and fauna". Fauna is all of the animal life of any particular region or time. In botany, flora (plural: floras or florae) has two meanings. The first meaning, flora of an area or of time period, refers to all plant life occurring in an area or time period, especially the naturally occurring or indigenous plant life. The second meaning refers to a book or other work which describes the plant species occurring in an area or time period, with the aim of allowing identification. I'm not sure that the opening post will impress a lot of people. Use of caps, bold and a lack of reasoning generally has the opposite effect on scientists. There's a reason why this website has these calm blue colors and no flashy adds. <-- flashy green smiley But you did a good job for a troll... Only one serious spelling mistake, and up to 30% of the text in normal letters.

You still have to tell the dog to sit, go down or stay... I can imagine that it's really funny for an alien if they're able to do this with 6.7 billion people. Oh... waaaait a second. More serious now: The cool thing about English, or any other language that is popular, is that anyone within 100 lightyears can start studying it. (100 lightyears is an approximation for the 100 years ago that we started broadcasting things on radio - probably not the correct number of years though). The signals made by man years ago will reach an ever increasing audience, as more and more aliens (if they exist) will hear. In 100 years from now, everybody within 200 lightyears can hear us. In 900 years from now, every star system within 1000 lightyears will be able to tune in to Earth. I think therefore that chances increase quite rapidly that aliens speak English. The volume of space that can hear us increases with: [math]Volume = lightspeed\cdot{time^3}[/math] It now all depends on how fast they learn to decipher our babblings. I hope they don't think we're talking to them in all the crap we broadcast (imagine that aliens think that love songs are meant for them - the horror scenario that follows!)

I wish Israel good luck with stopping terrorism... I don't know any example in the history of mankind where any power has actually succeeded in stopping terrorism (which does not mean that the terrorists are right). Also, the amount of energy you have to spend to stop 1 man from firing 1 rocket is mindboggling... (And our society seems willing to pay for it).

I like to think that it's some kind of airmiles system where you just get a leap second because you've earned it through consuming enough seconds in your life. I'm now saving for my leap decade. Sorry for not taking this thread very serious. It's a bit of a leap thread if you ask me.

First off, I probably know little about it. But I'd like to make a few obvious remarks. Wikipedia came up with a few interesting points as well. 1. Copypasted directly from Wikipedia: Over the 5 billion years (or 1.6E17 seconds) that our sun has been around, this object can have moved away approximately 1.6E17 * 500 km = 7.9E19 km away, if it would have had a constant linear velocity. That's the equivalent of over 8 million light years. I also know that the escape velocity for the milky way is 1000 km/s (approx.) so the object is likely to be still around somewhere in the galaxy. I just wanted to point out that it can be practically anywhere if we started off with a phenomenon ("kick") like I just mentioned. 2. The remark by Mr Skeptic: Supernovae blast material into the galaxy at high speeds. In addition to the "compact object" having a high velocity, the gas clouds also have a high velocity. 3. Another interesting piece of text is a description about motion of stars. What it comes down to is that stars near us move around pretty much randomly. I guess motion of stars is a bit like gas molecules. Individually they all move randomly (I believe that some stars even move towards us), but in convection, there is an average motion in a certain direction. We see that in the movement of the whole galaxy that spins around the center.

I agree with the plan of attack: first improve long distance transportation, while you think about cities. Cities are slowly being taken down and rebuilt anyway, so that is the right moment to also improve infrastructure in those urban areas. Interesting link about the speed records! There still exists another wikipedia website that claims that the French are the current record holders. Well... I guess that they're the record holders for something on wheels, while the Japanese actually fly their (maglev) trains

That's great news Heat and mass transfer problems can be a real pain I remember how happy I was when I passed the exam. I swore never to get a job where I need that stuff... of course, I failed, and I need it a lot.

Hehe, indeed. I've heard of an incident with a Ryanair airplane that had to make an emergency landing after it had sucked in a swarm of starlings , which is a common bird that flies around in large groups in Europe... These birds are 60-90 grams on average. If a jet airliner has to land because an engine stalled because of 60-90 gram birds, then it has been a massacre. Thousands of birds may have died in that incident. Nobody closed down that airport Article (in Dutch): http://www.depers.nl/buitenland/259986/Vliegtuig-maakt-noodlanding-in-Rome.html

Since the state of Israel has been founded both sides have started this conflict. There has never been a moment where either side did not take any action at all. There were always some terrorists or colonists (which is pretty much the same thing). One side shoots rockets at civilians, the other locks up millions of civilians in the world's largest open air prison. If you think Israel is the good guys, then building a wall is defense, and rockets are bad (m'kay?), if you think Palestinians are the good guys, then you think that this wall is against human rights and rockets are defense. I think that both Israelis and Palestinians are a bunch of nutcases to fight over such a crappy piece of land for so long.

You separate the glycerol so that more glycerol is coming out of solution? In a 2 phase system, the removal of one of the phases does not influence the second phase's equilibrium. However, it is true that this equilibrium needs time, so waiting is always a good idea... but it is not necessary to drain off a part of the glycerol to improve the separation.

Just close off the fermenter, and see if growth continues? If growth is purely aerobic, then there should be a (linear?) relation between growth and oxygen supply... right? Disclaimer: I'm a chemical engineer, not biochemical.

Mean velocity of a gas molecule is only governed by temperature. When you expand a gas, it cools down, so that slows the molecules. But if you compare two molecules, one in say 1 bar, the other in 0.5 bar, both at the same temperature, then they'll have the same (average) velocity. There is a formula to calculate the mean velocity of a gas molecule (and some more formulas to calculate something almost the same, their differences have to do more with statistics than with physics): [math]\overline{v}=\sqrt{\frac{8\cdot{R\cdot{T}}}{\pi\cdot{M}}}[/math] Note that pressure is not in this formula. Attempting to substitute the R*T using the ideal gas law will give you: [math]\overline{v}=\sqrt{\frac{8\cdot{P\cdot{V}}}{\pi\cdot{M\cdot{n}}}}[/math] And in this second formula, the pressure is included, but it is divided by n, and multiplied by V. The term n/V is the number of molecules per volume. You see that in this substituted version, the molecule density (pressure) still cancel.

npts2020, can you provide a link to the claim that the Germans have tested their trains at such incredible speeds? And I'd like to say that many of our freight trains are electric. There exist also companies that operate on lines that have no electric infrastructure, so they use diesel locomotives. I also don't see your point of "why build it for huge trains that many people will not use"? Train lines between large cities have intercity trains every 15 minutes, and less in the night. These trains are often half full, and totally packed in the rush hours. That means that up to 10000 people travel on one line per day, which is in the same order of magnitude as highways... and the investment to build either a highway or a trainline is the same order of magnitude as well. Investments for a large amount of bridges might be just as high as a bunch of railroads. In both cases you design an infrastructure where you want to keep several flows of traffic separated (in one case, you separate N/S and E/W, in the other you separate trains from the rest). And I don't agree that you don't need as many cross streets. Reducing the amount of cross streets in urban areas will ultimately reduce efficiency because you reduce the options to get from A to B, and it will make the average path you have to travel longer. Not a good option, I think. And you're still left with the challenge to connect the N/S elevated roads with the E/W roads at ground level. Ramps at every street corner are the only way, but this needs a huge amount of space, which in many cases is already occupied by buildings.

Well... the newest Bond movie isn't much better. There's the hotel that is powered by fuel cells (so far nothing weird). But each room has its own individual fuel cell for power (isn't it easier to install some cables like most places have?) and their own hydrogen storage (obviously resulting in the whole place being blown up). Not really so much a chemistry mistake as a chemical engineering mistake.

hmm... that's a rather huge difference. (Much larger than I'd expect). Do you drive so fast, or is the train so slow, or the connection/transfer so bad? Or do you have to walk so far on the other end of the line? In Europe, intercity and international trains should average about 80 km/h, I think (including stops and transfers), so you're not so much slower than driving, especially if you include a coffee break, fueling and possible traffic jams. And then there are the high speed trains which average at 250 km/h, and have top speeds well over 300 km/h. The high speed network is still expanding. Our public transportation only sucks inside cities (bus systems are a disaster, trams are slow and only the metro does its job sometimes, if you're lucky to live in a place where they have one). Then again, the bus is for the elderly who cannot walk so far, can no longer drive and have lots of time

You calculate the P (power) from the heat transfer coefficient. You use the Nusselt number to get the heat transfer coefficient for the liquid side of the rod... What is the Reynolds' number? If it's Re > 1000, you can assume a turbulent flow, and I certainly hope you can assume that. Laminar problems are so much more nasty. Then you use: P = U * A * dT P = power (W = J/s) U = (W/m2K) overall heat transfer coefficient (note: assume a constant temperature inside the rod, then you can say that the heat transfer coefficient of the liquid side equals the overall heat transfer coefficient - the real equation will be much more nasty, because you'll have a heat conductivity inside the rod, and the center of the rod is warmer than the outside, and you'll probably end up with a bunch of nasty differential equations describing the temperature profile inside the rod as a function of the width). A = area (m2) dT = temperature difference between the two sides across which you calculate the power (heat transfer) (Kelvins or deg C). Hope this helps. I am still clueless what kind of temperature profile you need: along the length of the system, or the width? (In reality, you get both! Which is why modeling this is so hard.) Also, I re-read the original question. Please note that I use Q for the heat (Joules), not for flow. Always specify the units and name of any symbol you use.

Why would you want to know the enthalpy change ([math]\Delta{H}[/math])? It just says how much heat develops (whether it cools or heats) when you dissolve the [ce]Ca(OH)2[/ce]. I don't recommend trying to derive this from thermodynamic formula's. Either look it up, or measure it. The easy way is to search in a Handbook, such as Perry's Chemical Engineers' Handbook. Since you probably don't have that book, and I do, I looked it up for you. Solubility of the anhydrous Ca(OH)2 (but anhydrous is the standard form - it does not have any crystal water) 0 deg C - 0.185 g / 100 g water 10 deg C - 0.176 g / 100 g water 20 deg C - 0.165 g / 100 g water 30 deg C - 0.153 g / 100 g water 40 deg C - 0.141 g / 100 g water 50 deg C - 0.128 g / 100 g water 60 deg C - 0.116 g / 100 g water 70 deg C - 0.106 g / 100 g water 80 deg C - 0.094 g / 100 g water 90 deg C - 0.085 g / 100 g water 100 deg C - 0.077 g / 100 g water If you use this data, please include the reference: "Perry, Green, Perry's Chemical Engineers' Handbook, 7th Edition, McGraw-Hill, 1998, New York" because that's where I found this. Disclaimer, I might have gotten the official order of the reference wrong (I never know what comes first: publishers, or year or so).

Impressive, how we all thought that we got 1 second "for free", and now we wasted several minutes talking about it in this thread. The leap second is a fraud, and we were all tricked by it!

So, we got a situation of one country wanting to completely destroy an institution (Hamas) that has the support of perhaps the majority of the neighbouring country. That institution has several wings, one of which tried to do politics, the other shoots rockets at civilians. And we got a situation where both sides try to disrupt the lives of civilians of the other side (Palestinians throwing rockets, Israelis building walls to turn parts into prisons or ghettos). The west is saying that they want a democracy, as long as it's not Hamas. We also say that the Israelis should stop attacking, but they're correct to defend themselves. I don't agree with the current course of action of Israel. Also, I obviously think that throwing random rockets to the neighbours is not very constructive (euphemisms rule). All in all... except the military intervention by both western countries and middle eastern countries, I see no way out. My biggest fear is that it escalates. That some idiot in another neighbouring country will attack Israel.

Well... the water is flowing - that is convection. So, yes, the problem is very much related to convection. Q = heat, in J. There are 2 formulas that are almost the same: Q=m*Cp*(T(start)-T(end)) where Q = heat (energy), in J, this is for a certain amount of mass (m, in kg) and: P=F*Cp*(To-Ti) where P = power, in J/s, or Watt (W)... this is for a mass flow (F, in kg/s) Since you have a flow, I'd go with the 2nd formula. But those formulas will not give you a temperature profile. It'll give the average temperature... I still don't completely understand the problem, but you probably need time-dependent formulas (differential equations). If you're really interested in the temperature profile, then you'll simply have to study the steps I mentioned. There are loads of wikipedia websites. Search on "Reynolds number", "energy balance" and "heat transfer" and then click a bunch of other links on those websites. Sorry for not explaining the entire theory of heat transfer. It's a university study which takes a bit of time to understand (so also: don't despair when you don't understand it in 1 day! That's normal!)

Those are not two processes I'd integrate. Just make methanol first, purify it by standard means (distillation or extraction) and then add it to your biodiesel reactor. Also, the difference in temperature between the destructive distillation (which is also called pyrolysis, or cracking and operates at 400 deg C, or more) and the biodiesel (60 deg C) also means you'd have to separate the processes in order not to lose all your heat, or to prevent overheating of the biodiesel reactor. But making methanol from a sustainable source by means of pyrolysis is a good idea which is being investigated as we speak. And having a sustainable source for methanol would obviously make the biodiesel even more green.

I'd get a car, and make a run straight for the heavy chemical industry. If there are that many zombies, then you need that much firepower. Turning one refinery into a twenty Gigawatt flamethrower might do the job. (Plus that the access to the industry is narrow, making it easy to aim). The plan assumes that zombies don't swim. And in addition, there is a canteen and kitchen, and the place has its own power generators and backup generators...

You know, this very much shows the main problem. Hamas was actually an elected government. The government of Palestine is being called a terrorist organization. According to our "modern" definitions of terrorists, the only people with any authority in Palestine are in fact terrorists. In Palestine, there exist two types of people: terrorists and civilians. According to our "modern" way of handling terror, the only option would be a total defeat of Palestine... which obviously is not acceptable for Palestinians.

Hehe, ships are more limited in your country perhaps. There are some places where it does work. Click for an aerial picture of Amsterdam. But I agree with npts2020. Ships should only be used where possible, and the options are limited. Regarding the personal automated transit, I have two points to make... First, in case of a completely personalized system, you'll be needing the same grid as our normal roads... which simply means you'll have lots of corners and crossings like we have today. If the grid is the same, then the paths of (automated) vehicles will certainly cross. This brings a danger, which is now covered by traffic lights and traffic laws. If cars won't stop for a crossing, then you either have to build a bridge (highway style) or weave the twelvestreams of cars such that they never collide. Sorry, but I really doubt any engineer would ever attempt to design this. Not with real living people in the vehicles. For cargo, perhaps it can be done... (Twelve streams of cars: two roads, traffic in two directions is 4 streams arriving at the crossroad. Then each stream can go in 3 directions: left, right and straight). A chance that there is a break down will be almost unacceptable at increased speeds and densely packed roads... Therefore, I suggest that much more bridges, flyovers, or whatever elevated roads need to be built... The point I'm making here is that it's not going to fit in our cities... you cannot automate each and every crossroad using bridges and tunnels. You would not have to rebuild the roads, but the entire country. Second, compared to a train, a personal vehicle will have more air resistance. This will increase fuel consumption... Unless people can have some G-forces, you need to slow down and speed up again at every corner... same as now. There is no increased efficiency in this idea. I do think that automating cars can have benefits... but I would study this only for the highways (or interstate roads or whatever you call them - those roads for longer distances where you can drive fast).

Passenger trains should be excluded, because they're less efficient. (They carry chairs and other things for comfort (and even a toilet!), they have lights and airco, etc... not likely to be equally efficient). And you should compare it to a truck, not a normal car. But I do believe that ships are even more efficient for transporting cargo, even upstream on major rivers. (Sorry, no link to back up my claim).