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Model Forum / General / Models / February 2010Selecting bigger alder seeds by their falling speed in air
I wonder if anybody on this group can help me with this? I want to find bigger alder seeds and breed from them to produce even bigger alder sees. You can get huge numbers from a tree, The Forestry commission breeds from the best 1 in 400 000 trees and that's the sort of numbers I want to go through. I want a mechanised way of doing at least some of that sorting. The seeds are all the same colour and very difficult to sort by eye, and they vary in thickness. I want seeds which are heavier = thicker, so it seems best to sort by falling speed in air. In a room 3 M high I have put alder seeds into a teaspoon and tipped it. This removes the doubt as to whether the seeds fell immediately I opened my grip or whether they were stuck onto my finger. I had a big sheet of paper on floor and the seeds make a tap noise when they hit that paper. I time the time from tipping the teaspoon to the sound of the seeds hitting the paper. It was just over 1 second, so a falling speed of 3M/second. Obviously not a very exact measurement, but it can't be too far out. (I have bought fans from R S Components which, as rated, can produce airspeeds of 10M/sec though a crossesection of 7 cm x 7 cm, but I am not sure R S Components's ratings are correct) These are "standard" seeds. I want to search for bigger seeds with a faster falling speed. I want this winnower to be portable, so that if I find a tree which has bigger seeds, I can look for more from that tree and not waste time on trees which produce small seeds. The idea that I am toying with at the moment is this:- There will be a fan at the top, pulling air up and OUT. The small discards will be blown through it. Below that will be square-sided upside-down pyramid of perspex so that I can see what is going on inside. There will also be a chute for putting the seeds to be tested in. Airflow will be inwards, so no problem about that. The pyramid will taper down to the sorting zone, where falling speed will be tested. This will be parallel-sided. This is the point that I want advice about. Can the airflow be laminar? The depends on the width of the sorting section and Reynold's number. I am not used to calculations involving Reynold's number and I couldn't trust my answer. How wide does it have to be for an airflow of 3M/sec to be laminar? Help please! The answer must be either that the width is reasonable (it is something I can carry round with me) or it is not. * The flow can be laminar at a reasonable width. But is this desirable? Doesn't it mean that a seed with a falling speed of about 3M/sec will be blown up if it falls at the centre, drift to the side and fall down the side where the air speed is lower? That's the sort of sophistication that I want advice on. But to take the simplest view, I will have a short length of sorting section, with a taper leading into it, and well below it a catching bowl to catch the bigger seeds that have fallen through. (I can go out seed-collecting in moderate winds). Or else I can use 1mm wire mesh (cut from the bottom of a kitchen strainer) to catch the seeds at the bottom of the sorting section. Like this :- Cone and Fan \ / \ / | | | Sorting | | section | | | | | | | | | / \ / \ / \ / \ Air-smoothing entry cone. | | |_________________| Catching bowl * The flow cannot be laminar at a reasonable width. This does at least mean that the airspeed will be constant, though turbulent, right across the width. But how can I get a reasonably sharp cut-off? (I say "REASONABLY sharp cut-off" because in practice, to be sure I am not eliminating seeds that would be useful to me, I will adjust the airspeed to allow through a small number of the upper end of the "normal distribution". Does it help to make the sorting section longer so that seeds are bounced up and down and tested many times? So, help, comments, answers, redirection to a site where they KNOW about these things - all would be welcome. Michael Bell  Signature-- Michael. I don't want to spoil your dreams, but have you proved the basic premise behind your machine that heavier seeds fall faster than smaller ones? 500 years ago a man called Galileo Galilei reputedly dropped different size iron balls from the leaning Tower of Pisa and demonstrated to the world that they fell at the same rate. Admittedly air resistance will play a bigger part in the descent of seeds than iron balls, but I doubt the difference is so marked that it could be used for grading, so I ask again: have you proved that thicker seeds fall faster than thin seeds? I'd hate to see you waste time and money on a machine that does not work. Cliff Coggin. >I wonder if anybody on this group can help me with this? > [quoted text clipped - 6 lines] > which are heavier = thicker, so it seems best to sort by falling speed > in air. Cliff All praise to you for your scepticism, but :- 1) Without air resistance an object will fall 5 Metres = 16 feet in the first second. 2) I just quoted the FIRST tap on the paper on the floor. It takes another 2 seconds for all of them to come down. 3) Winnowing is a well-known process for separating wheat from chaff. Michael > Michael. > I don't want to spoil your dreams, but have you proved the basic premise > behind your machine that heavier seeds fall faster than smaller ones? 500 [quoted text clipped - 5 lines] > that thicker seeds fall faster than thin seeds? I'd hate to see you waste > time and money on a machine that does not work. > Cliff Coggin. >>I wonder if anybody on this group can help me with this? >> [quoted text clipped - 6 lines] >> which are heavier = thicker, so it seems best to sort by falling speed >> in air. -- OK, as long as you appreciate the sometimes non-intuitive concept that heavy bodies do not necessarily fall faster then similar lighter bodies. As an aside, the acceleration due to gravity is twice the figure you quoted i.e. 32 feet/second/second. Cliff. > Cliff > [quoted text clipped - 39 lines] > > -- > OK, as long as you appreciate the sometimes non-intuitive concept that heavy > bodies do not necessarily fall faster then similar lighter bodies. > > As an aside, the acceleration due to gravity is twice the figure you quoted > i.e. 32 feet/second/second. > In fairness he quoted a Distance 16ft I think. when I was in school some 55yrs agoI learned that S= ut + 1/2 a t squared Don > Cliff. > [quoted text clipped - 44 lines] >>>> in air. >>>> >> OK, as long as you appreciate the sometimes non-intuitive concept that >> heavy bodies do not necessarily fall faster then similar lighter bodies. >> As an aside, the acceleration due to gravity is twice the figure you >> quoted i.e. 32 feet/second/second. > In fairness he quoted a Distance 16ft I think. when I was in school some > 55yrs agoI learned that S= ut + 1/2 a t squared You must have gone to the same school as did I, or else also sat the London University 'A' Level maths. Also off the top of my head 40 years later ... v = u + a t v^2 = u^2 + 2 a s But you are both right a = 32'/s^2 s after one second = 16' >>> OK, as long as you appreciate the sometimes non-intuitive concept that >>> heavy bodies do not necessarily fall faster then similar lighter bodies. [quoted text clipped - 5 lines] > You must have gone to the same school as did I, or else also > sat the London University 'A' Level maths. 'O' level physics? > Also off the top of my head 40 years later ... > > v = u + a t > v^2 = u^2 + 2 a s I only remember the S = ut + 1/2 at^2 one - but it's about all you need to remember, you can work out the others (or even just the numbers) from it. -- Peter Fairbrother >>>> As an aside, the acceleration due to gravity is twice the figure you >>>> quoted i.e. 32 feet/second/second. [quoted text clipped - 13 lines] > I only remember the S = ut + 1/2 at^2 one - but it's about all you need to > remember, you can work out the others (or even just the numbers) from it. Mea culpa. The distance travelled in one second would indeed be 16 feet. The result seemed so obvious to me that I didn't bother to actually calculate it. My apologies. Incidentally, when I did O level physics some 43 years ago in London I seem to remember the abbreviation for acceleration was f, so the above equation would have been s = ut + 1/2f(t squared). Is my memory failing or was it just one of those conventions that changed over time? Just to stir up memories for the older generation, I also recall force as a result of weight being expressed in poundals. Cliff. > >> [quoted text clipped - 36 lines] > > Yes the FPS system if I remember rightly (Foot-Poundal-Second), I started with the symbol "a" for acceleration which changed to "f" some years after. Don > >> [quoted text clipped - 22 lines] > > How do you manage to insert the square symbol (little 2 after and above the v and u) It dissapears when I reply. Don >> a = 32'/s^2 > How do you manage to insert the square symbol (little 2 after and above > the v and u) > It dissapears when I reply. > Don It depends on your newsreader, but the normal way is to use the caret ^ character to denote a superscript. So it's s ^ 2 without the spaces, s^2. Some newsreaders also allow the use of the underscore _ to denote subscripts, but not many. Both of these conventions were popularised by TeX, though the caret was used earlier in Algol. How nerdy that I know that! -- Peter Fairbrother >>> a = 32'/s^2 > [quoted text clipped - 13 lines] > > How nerdy that I know that! Even nerdier. For an example of multiple sub- and super- scripts, it's probably about as complex as it gets. This is the final version, as a .png: http://www.zenadsl6186.zen.co.uk/rect1875.png And this is the LaTeX required to create it: http://www.zenadsl6186.zen.co.uk/ICURmath -- Peter Fairbrother >>>> OK, as long as you appreciate the sometimes non-intuitive concept that >>>> heavy bodies do not necessarily fall faster then similar lighter [quoted text clipped - 23 lines] > It dissapears when I reply. > Don It's an up-arrow, Shift 6 on the UK keyboard Cliff At the end of its first second's fall in a vacuum, an object will be falling at 10 Metres/sec, and at that time it will actually have fallen 5 Metres. But we are both on the same side, so I don't want to start a flame war. Michael > OK, as long as you appreciate the sometimes non-intuitive concept that heavy > bodies do not necessarily fall faster then similar lighter bodies. > As an aside, the acceleration due to gravity is twice the figure you quoted > i.e. 32 feet/second/second. > Cliff. >> Cliff >> [quoted text clipped - 39 lines] >> >> -- -- No war or criticism intended Michael. Fortunately this newsgroup is open to discussion and even argument without getting offensive, though it does mean that threads often drift off topic. Have you considered a centrifugal separator for your seeds? http://process-equipment.globalspec.com/datasheets/2901/HosokawaMicronPowderSyst ems/810BAA60-0540-4E5D-8EEC-2126D3D5E286 is an industrial machine, but it shows the concept.If you could make something suitable it would probably be more compact than the machine you envisage, though somewhat more expensive. Cliff. > Cliff > [quoted text clipped - 65 lines] > > -- Thank you for this link. It has to be a portable machine, powered by a little 12 volt lead-acid battery. I want to be able to do a full day over ground which will not always be even Michael Bell > No war or criticism intended Michael. Fortunately this newsgroup is open to > discussion and even argument without getting offensive, though it does mean > that threads often drift off topic. > Have you considered a centrifugal separator for your seeds? > http://process-equipment.globalspec.com/datasheets/2901/HosokawaMicron > PowderSystems/810BAA60-0540-4E5D-8EEC-2126D3D5E286 > is an industrial machine, but it shows the concept.If you could make > something suitable it would probably be more compact than the machine you > envisage, though somewhat more expensive. > Cliff. >> Cliff >> [quoted text clipped - 65 lines] >> >> -- -- > I wonder if anybody on this group can help me with this? > > I want to find bigger alder seeds and breed from them to produce even > bigger alder sees. I googled for a few secs and came up with :- http://www.hannafords.com/seed-grading-history.php as a start. This has surely been done before, no point in reinventing the wheel . In a place where I worked for many years we had masses of machinery for sorting seeds of many different grasses, clovers and cereals using blowers, screens, even iron filings and magnets (surface roughness). Cheers Don >> I wonder if anybody on this group can help me with this? >> [quoted text clipped - 10 lines] > Cheers > Don Have a look here : http://science-in-farming.library4farming.org/Seeds_2/THE-PROCESSING-OF-SEEDS/Eq uipment-for-Cleaning-Seeds-1.html Don >> I wonder if anybody on this group can help me with this? >> [quoted text clipped - 9 lines] > Cheers > Don I've looked at this link. It doesn't explain their processes, and I couldn't get their CAPTCHA ("TYPE IN WHAT YOU SEE") to accept my input. You once did seed sorting yourself? I hear they have rather tough standards of purity for sale to the public, like "no more than ONE rat per tonne of wheat!" Michael Bell -- > >> [quoted text clipped - 24 lines] > Michael Bell > I wasn't personally involved in seed sorting, but it went on in our plant breeding research establishment. Our physics dep wksp was called on to design and make small bench type sorters in perspex to facilitate precise separation of various seed types. I think that you will see in my second link some of the basic principles in seed cleaning and separation. Hope this helps. Don >I wonder if anybody on this group can help me with this? > [quoted text clipped - 6 lines] > which are heavier = thicker, so it seems best to sort by falling speed > in air. Is there any proven correlation between the size of a seed and the subsequent size, many years later, of the consequent tree? Eating the flesh of a brave man did not create bravery. (And I wonder about the gullibility of the 21s C educated females who seem to be receptive to the presence of, "Pearl Protein" in their shampoos.) >>I wonder if anybody on this group can help me with this? >> [quoted text clipped - 6 lines] >> which are heavier = thicker, so it seems best to sort by falling speed >> in air. > Is there any proven correlation between the size of a seed and the > subsequent size, many years later, of the consequent tree? No correlation whatever. I am interested in the seeds only as a food source. BUT seed size has an interesting ecological consequence. "Forest trees" of the "climax vegetation", ie, the state the land will eventually reach if not disturbed by man, have big seeds, think of acorns and chestnuts because they need to for their seedlings to grow in heavy shade and through years worth of leaf litter to reach earth. Such seedlings can grow in the shade of their parents. Alders cannot, they have very light seeds, so easily scattered, but their food reserves are small so they can only grow on fresh ground, they are a "weed tree". The only place where alders form the climax vegetation is birch-alder carr, where they form a long-lasting forest only because they can survive wet ground. Michael Bell -- > I am interested in the seeds only as a food source. You can eat alder seeds? I didn't know that. How big are they anyway? How heavy? -- Peter Fairbrother > Eating the flesh of a brave man did not create bravery. Well that answers the question about the Chicken Tikka.................... John S. >I wonder if anybody on this group can help me with this? > [quoted text clipped - 6 lines] > which are heavier = thicker, so it seems best to sort by falling speed > in air. Is it proven that bigger seeds produce bigger trees? Would a rattle box be easier? You would need to vibrate a tub and the heaviest seeds would sink? But then are there lightweight big seeds to worry about? >>I wonder if anybody on this group can help me with this? >> [quoted text clipped - 8 lines] >> > Is it proven that bigger seeds produce bigger trees? > Would a rattle box be easier? You would need to vibrate a tub and the > heaviest seeds would sink? A "rattle box"! What's that? Michael Bell -- > (I have bought fans from R S Components which, as rated, can produce > airspeeds of 10M/sec though a crossesection of 7 cm x 7 cm, but I am [quoted text clipped - 4 lines] > Reynold's number and I couldn't trust my answer. How wide does it have > to be for an airflow of 3M/sec to be laminar? Help please! According to my calculations the Reynolds number will be greater than 4000 i.e. fully turbulent in any pipe bigger than 2cm across at that airspeed. In a 10cm diameter pipe it would be about 20,000. So basically you can't achieve laminar airflow and I suggest it isn't an issue anyway. The Reynolds number of the flow around the seed is probably another issue but not something you can control given you need a specific air speed. It might be easier to make if you just have a wire mesh inside the sorting tube you can chuck a bunch of them onto, turn on the motor, gradually increase the airspeed with a dial and wait for the small ones to be sucked out of the top. No shute for introducing seeds, just switch it on and off and put another batch in from the top or bottom. You could then actually grade them into batches at different air speeds if you can collect the ones that get sucked out. SignatureDave Baker > Can the airflow be laminar? The depends on the width of the sorting > section and Reynold's number. I am not used to calculations involving > Reynold's number and I couldn't trust my answer. How wide does it have > to be for an airflow of 3M/sec to be laminar? The transition from laminar to turbulent flow for air in a pipe at 3 m/s begins at about 1.15 cm pipe diameter. The pipe should be *narrower* than that for laminar flow, not larger. You ain't going to get laminar flow. The good news is that you neither need nor want laminar flow. Help please! Reynold's number for a pipe can be calculated using the formula R = duD/m Where d is the density (1.23 kg/m^3 for air) u is the velocity of flow D is the diameter of the tube (technically the hydraulic diameter, qua google if interested, but for a square tube it's equal to the side of the square) and m is the dynamic viscosity of the fluid (~0.000018 kg/ms for air) Flow becomes turbulent at above ~ Re = 2,100, and fully turbulent at above ~ Re = 4,000. -- Peter Fairbrother >> Can the airflow be laminar? The depends on the width of the sorting >> section and Reynold's number. I am not used to calculations involving >> Reynold's number and I couldn't trust my answer. How wide does it have >> to be for an airflow of 3M/sec to be laminar? > The transition from laminar to turbulent flow for air in a pipe at 3 m/s > begins at about 1.15 cm pipe diameter. > The pipe should be *narrower* than that for laminar flow, not larger. > You ain't going to get laminar flow. > The good news is that you neither need nor want laminar flow. > Help please! > Reynold's number for a pipe can be calculated using the formula > R = duD/m > Where d is the density (1.23 kg/m^3 for air) > u is the velocity of flow > D is the diameter of the tube (technically the hydraulic diameter, qua > google if interested, but for a square tube it's equal to the side of > the square) and > m is the dynamic viscosity of the fluid (~0.000018 kg/ms for air) > Flow becomes turbulent at above ~ Re = 2,100, and fully turbulent at > above ~ Re = 4,000. > -- Peter Fairbrother Thank you very much for this. In my scrap box I find I have a round tube plastic tube diameter 2.5 cms and length 30 cms, which is quite wide enough for cones to fall through. I am hope to keep out clusters of cones but there will always be detached cones. On full volts the fan (Sunon KDE1208PKV, RS Components 544-1018, a computer cooling fan) can pull seeds right through (and so to waste) but can only just lift full-size seeds through a hole of this diameter, obviously there's a lot of drag. So I want to ease the entry (and start uniform flow across the tube as soon as possible) by putting a cone around the entry like this :- | | | | | | | | / \ / \ / \ / \ What thoughts? Michael Bell -- >>> Can the airflow be laminar? The depends on the width of the sorting >>> section and Reynold's number. I am not used to calculations involving [quoted text clipped - 54 lines] > > Michael Bell The discharge coefficient of a square edged orifice plate or pipe is about 0.6. That of a well rounded entry or a conical entry like a venturi tube can be close to 1.0. Obviously if you're trying to suck seeds up off a surface you can't if the entry is conical because the air speed at the entrance would be too low but just rounding the ends of the pipe to as large a radius as possible or even adding a formed radius shape at the end with additional material would increase the discharge coefficient without dropping the air speed. If you're introducing the seeds part way up none of the above is an issue. I do have a different idea for you though. If you have a horizontal pipe with a light airflow going through it and you introduce seeds at one end you can grade them by how far away they land. Heavy seeds would land closer to the pipe. Light ones should blow away further. It would be easy to try anyway to see if it works. It might be too variable though but who knows. Another thought is an angled pipe which gradually steps up in diameter. Suck seeds in from the bottom and they will rise to the portion of a diameter which matches the airspeed to their mass and sit on the step at the base of that section. Not sure how you get them back out again though - lol. Small hatch covers in the pipe maybe. I could spend far too long thinking of ways to skin this particular cat. SignatureDave Baker >>>> Can the airflow be laminar? The depends on the width of the sorting >>>> section and Reynold's number. I am not used to calculations involving [quoted text clipped - 54 lines] >> >> Michael Bell > The discharge coefficient of a square edged orifice plate or pipe is about > 0.6. That of a well rounded entry or a conical entry like a venturi tube can [quoted text clipped - 4 lines] > material would increase the discharge coefficient without dropping the air > speed. > If you're introducing the seeds part way up none of the above is an issue. That's what I am doing. > I do have a different idea for you though. If you have a horizontal pipe > with a light airflow going through it and you introduce seeds at one end you > can grade them by how far away they land. Heavy seeds would land closer to > the pipe. Light ones should blow away further. It would be easy to try > anyway to see if it works. It might be too variable though but who knows. > Another thought is an angled pipe which gradually steps up in diameter. Suck > seeds in from the bottom and they will rise to the portion of a diameter > which matches the airspeed to their mass and sit on the step at the base of > that section. Not sure how you get them back out again though - lol. Small > hatch covers in the pipe maybe. > I could spend far too long thinking of ways to skin this particular cat. Thank you for all this, but these ideas need to be kept level and this is to be a PORTABLE device. Michael Bell -- >>>> Can the airflow be laminar? The depends on the width of the sorting >>>> section and Reynold's number. I am not used to calculations involving [quoted text clipped - 69 lines] > > I could spend far too long thinking of ways to skin this particular cat. What Dave said, though I'm not entirely clear about your question. I can foresee a possible problem though: I don't know how efficient this method of sorting might be. You will need a good speed controller, if I am imagining your device correctly, and it may not work well enough anyway. You might consider using lipo batteries - a fan takes about 200 mA at 12V, and a 11.1V 1500 mAh lipo is cheap enough (though the chargers ain't that cheap), and it will be very much lighter than a lead-acid battery. 1500 mAh would give you probably 5 reliable hours of use, and I don't imagine you'd be using it all the time. Can I ask again, first can you eat alder seeds? and second, how big and heavy are they, and the cones? -- Peter Fairbrother > I can foresee a possible problem though: I don't know how efficient this > method of sorting might be. You will need a good speed controller, if I [quoted text clipped - 10 lines] > Can I ask again, first can you eat alder seeds? and second, how big and > heavy are they, and the cones? Another thing, seed size is determined entirely by maternal genetics. You are going to be looking for seeds from a tree which are larger than the average seeds - isn't it easier to just collect seeds from trees which produce larger seeds? Why would you want to sort the seeds on-site anyway? Seed water content will make a big difference here too, likely more than genetics. I'm not at all clear what you are trying to do. -- Peter Fairbrother >> I can foresee a possible problem though: I don't know how efficient >> this method of sorting might be. You will need a good speed [quoted text clipped - 13 lines] > > Another thing, seed size is determined entirely by maternal genetics. and position on the tree, sunlight, phloem/xylem connections, and so on - but paternal genetic don't get a look in. > You are going to be looking for seeds from a tree which are larger than > the average seeds - isn't it easier to just collect seeds from trees [quoted text clipped - 8 lines] > > -- Peter Fairbrother >> I can foresee a possible problem though: I don't know how efficient this >> method of sorting might be. You will need a good speed controller, if I [quoted text clipped - 10 lines] >> Can I ask again, first can you eat alder seeds? and second, how big and >> heavy are they, and the cones? > Another thing, seed size is determined entirely by maternal genetics. NO! The tissues of the seed are 50 - 50 maternal/paternal, so 50 - 50 genetic contribution. You wouldn't say that an unborn baby was 100% its mother's genes! > You are going to be looking for seeds from a tree which are larger than > the average seeds - isn't it easier to just collect seeds from trees > which produce larger seeds? It certainly is true that some trees produce much bigger seeds than others, and of course it is those tree which I will focus on. But even within a tree producing large seed, some seeds are larger than others. > Why would you want to sort the seeds on-site anyway? Because I want to breed from them to make even bigger. > Seed water content will make a big difference here too, likely more than > genetics. There is no way I can control for water content. > I'm not at all clear what you are trying to do. I am trying to produce a variety of alder which will produce seeds as a grain. Plenty of trees produce fruit, apples, dates, palms, but none of them are staple crops, hard dry things with good keeping properties. This country cannot feed itself. 40% of its land is "upland" which cannot grow arable crops. Arable crops come from the Mediterranean and are at the limit of their range here. That is what I am trying to correct. Michael Bell -- >>> Can I ask again, first can you eat alder seeds? and second, how big and >>> heavy are they, and the cones? [quoted text clipped - 4 lines] > genetic contribution. You wouldn't say that an unborn baby was 100% > its mother's genes! My brother-in-law is emeritus professor of botany at Oxford University, and until he semi-retired recently was in charge of the Oxford arboretum. If he says the size and similar characteristics of seeds (apart from the embryo, which is tiny) are entirely determined by and made from maternal tissues, then I'm inclined to believe him. Not that I need an appeal to authority, because I know this anyway - seeds develop from the ovule, which is solely maternal tissue. (Also, I've been breeding ipomoeas for the last 18 years) >> You are going to be looking for seeds from a tree which are larger than >> the average seeds - isn't it easier to just collect seeds from trees [quoted text clipped - 3 lines] > others, and of course it is those tree which I will focus on. But even > within a tree producing large seed, some seeds are larger than others. Yes. This variation is mostly caused by micro-environmental factors, such as the position on the tree, how well-supplied the branch is, and so on. There may also be some contribution from epigenetic factors - but these are reset in the child, and so don't affect the morphology of future generations. >> Why would you want to sort the seeds on-site anyway? > > Because I want to breed from them to make even bigger. I get that - though not entirely, bigger seeds doesn't correlate with bigger yields per tree or per acre - but why sort them on-site? >> Seed water content will make a big difference here too, likely more than >> genetics. > > There is no way I can control for water content. Yes there is - dry them to a fixed dryness, then sort them at home. Takes a few weeks. >> I'm not at all clear what you are trying to do. > [quoted text clipped - 7 lines] > are at the limit of their range here. That is what I am trying to > correct. Laudable idea, but I don't think this is the right way to go about it. And what about the birds - siskins, redpolls, goldfinches, tits - which rely on alder seeds in the winter? -- Peter Fairbrother >>>> Can I ask again, first can you eat alder seeds? and second, how big and >>>> heavy are they, and the cones? [quoted text clipped - 4 lines] >> genetic contribution. You wouldn't say that an unborn baby was 100% >> its mother's genes! > My brother-in-law is emeritus professor of botany at Oxford University, > and until he semi-retired recently was in charge of the Oxford arboretum. > If he says the size and similar characteristics of seeds (apart from the > embryo, which is tiny) are entirely determined by and made from maternal > tissues, then I'm inclined to believe him. > Not that I need an appeal to authority, because I know this anyway - > seeds develop from the ovule, which is solely maternal tissue. The bulk of the alder seed is cotyledon, which is the tissue of the coming adult tree. Many other seeds are different. > (Also, I've been breeding ipomoeas for the last 18 years) That IS interesting. > Laudable idea, but I don't think this is the right way to go about it. > And what about the birds - siskins, redpolls, goldfinches, tits - which > rely on alder seeds in the winter? > -- Peter Fairbrother Whatever change you make, there will always going to be some losers. The little birds won't lose much in this case, they'll get a lot more seeds. But anyway, I think we should favour our own kind. Michael Bell -- >(Also, I've been breeding ipomoeas for the last 18 years) Ah - must be the man from ipomea then ;-) Regards, Tony >>>> Can I ask again, first can you eat alder seeds? and second, how big and >>>> heavy are they, and the cones? [quoted text clipped - 11 lines] > embryo, which is tiny) are entirely determined by and made from maternal > tissues, then I'm inclined to believe him. My apologies, I just learned that alder seeds have large-ish embryos, and I forgot to mention the role of the endosperm. First, some background on angiosperm seeds: 1) The embryo (which develops into the next generation) of an alder seed, like the tissues of the tree itself, is diploid, with one set of chromosomes from the female parent and one set of chromosomes from the male parent. 2) The endosperm (the food storage part) of an alder seed is triploid tissue, with two sets of chromosomes from the female parent and one set of chromosomes from the male parent. The two sets of chromosomes from the female parent in the endosperm are not the same as those of the female itself. The set of male-derived chromosomes in the endosperm is also different to the set of male-derived chromosomes in the embryo. 3) The seed coats develop from the integument of the ovary, and their genetics are entirely maternal. So a seed from an alder has parts with three different genetic makeups. The embryo of an alder seed is quite large compared to overall seed size, but it is fed from the endosperm, which is fed from the female parent. At seed maturity the endosperm is sometimes almost all gone, having been eaten up by the embryo, though this depends on species. In other seeds, like grains, the angiosperm comprises most of the seed. There is a small contribution to seed size from the endosperm genetics, via hormone levels, but these are not the same as the embryo genetics. There is also a contribution from embryo genetics, but this is typically minimal. Seed size in alders is almost entirely determined by maternal genetics, which determine the amount of food a seed gets from the mother plant, the characteristics of the coat and wing etc. (BTW, the thing which is usually called an "alder seed" is actually a nutlet, which is a seed with some other layers on top, and which is, apart from some parts of the seed itself, all maternal tissue) The point is that selecting based on seed size is not immediately passed down to the next generation, as seed size depends on maternal genetics. -- Peter Fairbrother > The point is that selecting based on seed size is not immediately passed > down to the next generation, as seed size depends on maternal genetics. There is a correlation though, but it's not immediate, only statistical, and it's usually small - in fact in some species it's negative, and in order to develop larger seeded plants you should collect smaller seeds! I don't think that applies to alders though, it's rare. I can ask. What species of alder are you looking at? What you should do is look at the trees and collect seed from the best trees with the biggest seeds. Then grow the larger seeds from those trees, but mainly because they grow faster. You might get lucky and find a sport with big seeds just by growing the very largest seeds from a tree, but I doubt it. It's going to take maybe 20 generations to see an improvement from selective breeding - and at 5 years per generation, that's 100 years at least before you get any results. By which time Britain may be in a jungle climate, depending on how global warming goes - who knows, it could be a desert if the clathrates let go. -- Peter Fairbrother >> The point is that selecting based on seed size is not immediately passed >> down to the next generation, as seed size depends on maternal genetics. > There is a correlation though, but it's not immediate, only statistical, > and it's usually small - in fact in some species it's negative, and in > order to develop larger seeded plants you should collect smaller seeds! > I don't think that applies to alders though, it's rare. I can ask. What > species of alder are you looking at? A glutinosa, but what about A. viridis, 3 years to fruiting! > What you should do is look at the trees and collect seed from the best > trees with the biggest seeds. Then grow the larger seeds from those > trees, but mainly because they grow faster. > You might get lucky and find a sport with big seeds just by growing the > very largest seeds from a tree, but I doubt it. The Forestry Commission select the best one in 400 000 of its trees. With this mechanised sorting method, I can hope to get through such numbers of seeds. I am also going to cross breed with other species, I might strike lucky. > It's going to take maybe 20 generations to see an improvement from > selective breeding - and at 5 years per generation, that's 100 years at > least before you get any results. My plan is to grow the seed, in June graft it onto the side-branches of adult trees which would be expected to produce next year's catkins, and the graft should do because next year's catkins for in June-July. They will breed next year, so breeding cylce = 2 years. Longer than I would like, but less than 5 years. > By which time Britain may be in a jungle climate, depending on how > global warming goes - who knows, it could be a desert if the clathrates > let go. > -- Peter Fairbrother Michael Bell -- >>>>> Can I ask again, first can you eat alder seeds? and second, how big and >>>>> heavy are they, and the cones? [quoted text clipped - 11 lines] >> embryo, which is tiny) are entirely determined by and made from maternal >> tissues, then I'm inclined to believe him. > My apologies, I just learned that alder seeds have large-ish embryos, > and I forgot to mention the role of the endosperm. > First, some background on angiosperm seeds: > 1) The embryo (which develops into the next generation) of an alder > seed, like the tissues of the tree itself, is diploid, with one set of > chromosomes from the female parent and one set of chromosomes from the > male parent. > 2) The endosperm (the food storage part) of an alder seed is triploid > tissue, with two sets of chromosomes from the female parent and one set > of chromosomes from the male parent. > The two sets of chromosomes from the female parent in the endosperm are > not the same as those of the female itself. > The set of male-derived chromosomes in the endosperm is also different > to the set of male-derived chromosomes in the embryo. > 3) The seed coats develop from the integument of the ovary, and their > genetics are entirely maternal. > So a seed from an alder has parts with three different genetic makeups. Rather like Maize. > The embryo of an alder seed is quite large compared to overall seed > size, but it is fed from the endosperm, which is fed from the female > parent. > At seed maturity the endosperm is sometimes almost all gone, having been > eaten up by the embryo, though this depends on species. In other seeds, > like grains, the angiosperm comprises most of the seed. > There is a small contribution to seed size from the endosperm genetics, > via hormone levels, but these are not the same as the embryo genetics. > There is also a contribution from embryo genetics, but this is typically > minimal. > Seed size in alders is almost entirely determined by maternal genetics, > which determine the amount of food a seed gets from the mother plant, > the characteristics of the coat and wing etc. A glutinosa has hardly any wing, unlike A. incana. > (BTW, the thing which is usually called an "alder seed" is actually a > nutlet, which is a seed with some other layers on top, and which is, > apart from some parts of the seed itself, all maternal tissue) > The point is that selecting based on seed size is not immediately passed > down to the next generation, as seed size depends on maternal genetics. What can you do to help me? Michael Bell -- >>>> Can I ask again, first can you eat alder seeds? and second, how big and >>>> heavy are they, and the cones? [quoted text clipped - 4 lines] >> genetic contribution. You wouldn't say that an unborn baby was 100% >> its mother's genes! > My brother-in-law is emeritus professor of botany at Oxford University, > and until he semi-retired recently was in charge of the Oxford arboretum. > If he says the size and similar characteristics of seeds (apart from the > embryo, which is tiny) are entirely determined by and made from maternal > tissues, then I'm inclined to believe him. > Not that I need an appeal to authority, because I know this anyway - > seeds develop from the ovule, which is solely maternal tissue. > (Also, I've been breeding ipomoeas for the last 18 years) >>> You are going to be looking for seeds from a tree which are larger than >>> the average seeds - isn't it easier to just collect seeds from trees [quoted text clipped - 3 lines] >> others, and of course it is those tree which I will focus on. But even >> within a tree producing large seed, some seeds are larger than others. > Yes. This variation is mostly caused by micro-environmental factors, > such as the position on the tree, how well-supplied the branch is, and > so on. Branch position certainly does make a difference, but even within one branch or even cone, there is variation in size. What causes that? Surely the pollen! > There may also be some contribution from epigenetic factors - but these > are reset in the child, and so don't affect the morphology of future > generations. >>> Why would you want to sort the seeds on-site anyway? >> >> Because I want to breed from them to make even bigger. > I get that - though not entirely, bigger seeds doesn't correlate with > bigger yields per tree or per acre - but why sort them on-site? So that when I find a tree with small seeds I can go on to the next, and when I find a tree with big seeds, I can spend some time on it. >>> Seed water content will make a big difference here too, likely more than >>> genetics. >> >> There is no way I can control for water content. > Yes there is - dry them to a fixed dryness, then sort them at home. > Takes a few weeks. >>> I'm not at all clear what you are trying to do. >> [quoted text clipped - 7 lines] >> are at the limit of their range here. That is what I am trying to >> correct. > Laudable idea, but I don't think this is the right way to go about it. Then suggest a better way to go about it. Michael Bell -- >> Yes. This variation is mostly caused by micro-environmental factors, >> such as the position on the tree, how well-supplied the branch is, and [quoted text clipped - 3 lines] > branch or even cone, there is variation in size. What causes that? > Surely the pollen! I'm pretty sure it's not the pollen, but I'll phone my brother-in-law later today and ask him for confirmation of this. I do know that he has told me that seed size etc is, in general, determined by the female parent. >> I get that - though not entirely, bigger seeds doesn't correlate with >> bigger yields per tree or per acre - but why sort them on-site? > > So that when I find a tree with small seeds I can go on to the next, > and when I find a tree with big seeds, I can spend some time on it. You'll still have to take things like water content into account. Are the seeds big because the tree is well watered? Are they big because the tree/branch etc is in a good position? And so on. I don't think choosing the biggest seeds from a single tree will help much. You want to choose a tree or ten which have big seeds, lots of seeds, seeds with the best nutritional value, which are not growing in especially favourable conditions, and collect seeds from those trees, and only them. Once you have chosen the trees, I don't think the size of the actual seed you use will matter very much. You will have a good maternal line, and I don't think the paternal line affects seed size much, if at all. Again, I will confirm this later today. It's not something I've had to consider for ipomoeas, just the pretty flowers. > Then suggest a better way to go about it. See above. BTW, have you eaten alder seeds? What do they taste like? I hear the catkins taste horrible ... -- Peter Fairbrother > BTW, have you eaten alder seeds? What do they taste like? > > -- Peter Fairbrother Probably chicken, most things taste like chicken..................... John S. >> BTW, have you eaten alder seeds? What do they taste like? >> [quoted text clipped - 3 lines] > >John S. ..except Co-op chicken :( -- Chris Edwards (in deepest Dorset) "There *must* be an easier way!" >>> BTW, have you eaten alder seeds? What do they taste like? >>> [quoted text clipped - 8 lines] > > Chris Edwards (in deepest Dorset) "There *must* be an easier way!" Even the neighbour's cat tasted like chicken, I told the wife we should expect Veal or rabbit >>> Yes. This variation is mostly caused by micro-environmental factors, >>> such as the position on the tree, how well-supplied the branch is, and [quoted text clipped - 9 lines] > I do know that he has told me that seed size etc is, in general, > determined by the female parent. Okay, just spoke to him. He says the effect of the pollen on seed size is "very little" - sometimes if the pollen is bad then it will make small seeds, but otherwise it has almost no effect on immediate seed size (though obviously it can affect the size of the seed in the next generation). One of the reasons for this is that the mother plant largely shuts down the genes from the pollen so they don't get expressed until the plant starts growing. Another is that the food supply to the developing seed is controlled by the mother plant. If the tree is "having a good time" it will produce bigger seeds, and this is the most influential factor in seed size. It's also why some seeds in a catkin are larger than others - they have a better food supply. He reckons that 20 generations of selection might see a significant increase in seed size in A. glutinosa, but he wouldn't be drawn on an estimate of how much. "He", btw, is professor emeritus of botany at Oxford, and keeper of the botanic gardens and arboretum there. He was also a bigwig at Kew for a while, don't know exactly what kind. He's one of, if not the, top authorities on this in the UK - I won't post his name here, but you can ask offlist. >>> I get that - though not entirely, bigger seeds doesn't correlate with >>> bigger yields per tree or per acre - but why sort them on-site? [quoted text clipped - 19 lines] > Again, I will confirm this later today. It's not something I've had to > consider for ipomoeas, just the pretty flowers. Yep, confirmed. You should still choose bigger seeds, but going for the very biggest is not likely to be useful in terms of their paternity. -- Peter Fairbrother >> Then suggest a better way to go about it. > [quoted text clipped - 5 lines] > > -- Peter Fairbrother >>>> Yes. This variation is mostly caused by micro-environmental factors, >>>> such as the position on the tree, how well-supplied the branch is, and [quoted text clipped - 9 lines] >> I do know that he has told me that seed size etc is, in general, >> determined by the female parent. > Okay, just spoke to him. > He says the effect of the pollen on seed size is "very little" - > sometimes if the pollen is bad then it will make small seeds, but > otherwise it has almost no effect on immediate seed size (though > obviously it can affect the size of the seed in the next generation). I will have to bear this in mind for follow-on breeding work, but not for first screening for bigger seeds: the tree whose seeds I am sampling now had a chain of ancestors going back... > One of the reasons for this is that the mother plant largely shuts down > the genes from the pollen so they don't get expressed until the plant > starts growing. Another is that the food supply to the developing seed > is controlled by the mother plant. > If the tree is "having a good time" it will produce bigger seeds, and > this is the most influential factor in seed size. It's also why some > seeds in a catkin are larger than others - they have a better food supply. It is MOST UNLIKELY that I would find THE TREE in which a mutation occurred. If a mutation has occurred, that mutation will probably appear in several trees which are not too far apart, the two will fertilise each other (though most of the pollen will come from unrelated trees) so a very small number of mutated seeds will be found in both trees. This is the kind of reason why it is so important to be able to screen through a very large number of seeds. And of course, some of the seeds which I think have promise will turn out badly. You must accept that with bulk screening. > He reckons that 20 generations of selection might see a significant > increase in seed size in A. glutinosa, but he wouldn't be drawn on an > estimate of how much. > "He", btw, is professor emeritus of botany at Oxford, and keeper of the > botanic gardens and arboretum there. He was also a bigwig at Kew for a > while, don't know exactly what kind. He's one of, if not the, top > authorities on this in the UK - I won't post his name here, but you can > ask offlist. I'll do that when I've got the immediate rush over. Michael Bell -- >>>>> Yes. This variation is mostly caused by micro-environmental factors, >>>>> such as the position on the tree, how well-supplied the branch is, and [quoted text clipped - 35 lines] > in both trees. This is the kind of reason why it is so important to be > able to screen through a very large number of seeds. No no no - even if you get a seed with big-seed mutations in both the pollen and the mother, it *won't* be any larger than a seed whose mother has a big-seed mutation and whose father doesn't. That's what I've been trying to tell you. Do you understand it? Please?? I have more useful stuff to say, but you have to understand that first. It's important to screen a very large number of trees, not seeds. That's what the forestry commission do. What you want to do is look for mothers who produce big seeds, not for the biggest seeds. (there most likely won't actually be one mutation, and a double mutation isn't necessarily going to give big seeds - or any seeds at all - but so-to-speak) -- Peter Fairbrother >>>>> Can the airflow be laminar? The depends on the width of the sorting >>>>> section and Reynold's number. I am not used to calculations involving [quoted text clipped - 69 lines] >> >> I could spend far too long thinking of ways to skin this particular cat. > What Dave said, though I'm not entirely clear about your question. > I can foresee a possible problem though: I don't know how efficient this > method of sorting might be. You will need a good speed controller, if I > am imagining your device correctly, and it may not work well enough anyway. I have a rheostat (R S Components 170-304) and I have on order a speed controller (Type KC5225 from Jaycar WWW.JAYCAR.COM.AU) > You might consider using lipo batteries - a fan takes about 200 mA at > 12V, and a 11.1V 1500 mAh lipo is cheap enough (though the chargers > ain't that cheap), and it will be very much lighter than a lead-acid > battery. > 1500 mAh would give you probably 5 reliable hours of use, and I don't > imagine you'd be using it all the time. The likely duty cycle is;- Pull cones off tree 2 minutes Crush cones 1 minute Run seed sorter 1 minute Walk to next tree 1 minute I have a 1.2 AH lead-acid battery. It's not too heavy. I can't see myself running out of juice at this rate, but I could have 2, one for the morning, one for the afternoon. Michael Bell -- > You ain't going to get laminar flow. > > The good news is that you neither need nor want laminar flow. What you may want is uniform flow. The way that is achieved in a decent wind tunnel is to have a contraction in the tube with a '2q' screen across it. Called '2q' because the pressure drop across it is twice the dynamic pressure (0.5?V^2) of the approaching airflow Can't remember the spec.of such a mesh for sure but it's pretty fine stuff. Something like 30 mesh 32 gauge Bigger seeds have more weight and more drag - which wins? Perhaps I should have followed some of the links given. Henry >> You ain't going to get laminar flow. >> >> The good news is that you neither need nor want laminar flow. > What you may want is uniform flow. > The way that is achieved in a decent wind tunnel is to have a contraction in [quoted text clipped - 3 lines] > Can't remember the spec.of such a mesh for sure but it's pretty fine stuff. > Something like 30 mesh 32 gauge I don't understand this. Should this mesh be at the intake from "still" air or where the inlet taper changes to parallel sides? I have 1 mm wire mesh. Maybe I could get different if I knew what was wanted. > Bigger seeds have more weight and more drag - which wins? > Perhaps I should have followed some of the links given. For spheres of the same density, the bigger spheres fall faster. It's a matter of weight/surface area. Michael Bell -- >>> You ain't going to get laminar flow. >>> [quoted text clipped - 12 lines] > I don't understand this. Should this mesh be at the intake from > "still" air or where the inlet taper changes to parallel sides? For your simple shape the best you can do is to place the mesh at the inlet. > I have > 1 mm wire mesh. Maybe I could get different if I knew what was wanted. 30 mesh means 30 wires per inch and 32 gauge (SWG) is about 0.010 inches ( 0.25mm) in diameter >> Bigger seeds have more weight and more drag - which wins? >> Perhaps I should have followed some of the links given. > > For spheres of the same density, the bigger spheres fall faster. It's > a matter of weight/surface area. It's actually a matter of weight/frontal area. Surface area is proportional to 'width' cubed. Frontal area is proportional to 'width' squared The conclusion is the same provided the seeds have the same density. My question really boils down to questioning if the seeds have the same density independent of size. Henry >My question really boils down to questioning if the seeds have the same >density independent of size. > >Henry I'm curious that no one has suggested using a cyclone. A light tin can is easily transportable and by sizing the cone angle and pipe diameters appropriately they can be made to be very selective and have no filters or screens to get blocked or contaminated. It's donkey's years since I did any analysis on such a thing, but I should imagine it's easy enough to unearth if you look. Richard --- news://freenews.netfront.net/ - complaints: news@netfront.net --- >>My question really boils down to questioning if the seeds have the same >>density independent of size. >> >>Henry > I'm curious that no one has suggested using a cyclone. A light tin can > is easily transportable and by sizing the cone angle and pipe > diameters appropriately they can be made to be very selective and have > no filters or screens to get blocked or contaminated. > It's donkey's years since I did any analysis on such a thing, but I > should imagine it's easy enough to unearth if you look. > Richard It's a possible design. But air would flow into the outlet at the bottom for the heavies so I would have to put a glass jar at the bottom to collect them. However I have gone so far down this route that I don't want go another way. Michael Bell -- >>>> You ain't going to get laminar flow. >>>> [quoted text clipped - 12 lines] >> I don't understand this. Should this mesh be at the intake from >> "still" air or where the inlet taper changes to parallel sides? > For your simple shape the best you can do is to place the mesh at the inlet. >> I have >> 1 mm wire mesh. Maybe I could get different if I knew what was wanted. > 30 mesh means 30 wires per inch and 32 gauge (SWG) is about 0.010 inches ( > 0.25mm) in diameter >>> Bigger seeds have more weight and more drag - which wins? >>> Perhaps I should have followed some of the links given. >> >> For spheres of the same density, the bigger spheres fall faster. It's >> a matter of weight/surface area. > It's actually a matter of weight/frontal area. > Surface area is proportional to 'width' cubed. > Frontal area is proportional to 'width' squared > The conclusion is the same provided the seeds have the same density. > My question really boils down to questioning if the seeds have the same > density independent of size. > Henry I don't see how they could NOT have the same density independent of size. But it doesn't matter. I want seeds that contain food material, if a seed contained a lot of fluff, I wouldn't want it anyway. Michael Bell -- >>> Bigger seeds have more weight and more drag - which wins? >>> Perhaps I should have followed some of the links given. [quoted text clipped - 3 lines] > It's actually a matter of weight/frontal area. > Surface area is proportional to 'width' cubed. ITYM Weight is proportional to 'width' cubed. > Frontal area is proportional to 'width' squared > The conclusion is the same provided the seeds have the same density. Nope, it's a standard square/cube law situation. Bigger seeds will fall faster in air, assuming the same density. -- Peter Fairbrother >>>> Bigger seeds have more weight and more drag - which wins? >>>> Perhaps I should have followed some of the links given. [quoted text clipped - 11 lines] > Nope, it's a standard square/cube law situation. Bigger seeds will fall > faster in air, assuming the same density. Actually it's not exactly that, but a complete analysis would take several pages of math. It's close though. Take a half-full jar of honey or syrup and shake it vigorously, then put it down. The big bubbles will rise fast, but the small bubbles will take a long time to rise. It's the same with seeds in air, except the other way up, and honey is thicker than air. -- Peter Fairbrother >>>>> Bigger seeds have more weight and more drag - which wins? >>>>> Perhaps I should have followed some of the links given. [quoted text clipped - 5 lines] >> >> ITYM Weight is proportional to 'width' cubed. For the same shapes so is surface area and Michael mentioned that. >>> Frontal area is proportional to 'width' squared >>> The conclusion is the same provided the seeds have the same density. >> >> Nope, it's a standard square/cube law situation. Bigger seeds will fall >> faster in air, assuming the same density. Indeed but I was conceding that althought Michael's analysis was flawed, heavy seeds fall faster if of the same density. You don't spend 30 years working in wind tunnels without learning some of the basics! Mind you that was a while ago now so can't claim to remember everything! > Actually it's not exactly that, but a complete analysis would take several > pages of math. It's close though. > Take a half-full jar of honey or syrup and shake it vigorously, then put > it down. The big bubbles will rise fast, but the small bubbles will take a [quoted text clipped - 4 lines] > > -- Peter Fairbrother > * The flow cannot be laminar at a reasonable width. This does at least > mean that the airspeed will be constant, though turbulent, right > across the width. But how can I get a reasonably sharp cut-off? Use a longish section, maybe 3:1 length/side or bigger. -- Peter Fairbrother (I say > "REASONABLY sharp cut-off" because in practice, to be sure I am not > eliminating seeds that would be useful to me, I will adjust the [quoted text clipped - 6 lines] > > Michael Bell >> * The flow cannot be laminar at a reasonable width. This does at least >> mean that the airspeed will be constant, though turbulent, right >> across the width. But how can I get a reasonably sharp cut-off? > > Use a longish section, maybe 3:1 length/side or bigger. Forgot to mention using a round tube would probably give better cutoff than a square one. -- Peter Fairbrother >>> * The flow cannot be laminar at a reasonable width. This does at least >>> mean that the airspeed will be constant, though turbulent, right >>> across the width. But how can I get a reasonably sharp cut-off? >> >> Use a longish section, maybe 3:1 length/side or bigger. > Forgot to mention using a round tube would probably give better cutoff > than a square one. > -- Peter Fairbrother Fine. Now the next stage of the design. My sorting tube has an internal diameter of 2.5 cms and the fan has an internal diameter of 8 cms, and I want to connect them with an inverted cone - actually an inverted pyramid because it will be square-sided. It would be nice for the seeds to settle in bands of different size in the cone that joins them, but in such turbulent flow that's asking for too much. So failing that, what I want to do is to do it in an energy efficient way, and that means an evase. What angle should it be? There is plenty of vertical space. What should the expansion angle be? It will probably be expressed as 1 in x rather than in degrees. Google acknowledges the meaning of the word, but I can find no way of calculating it. Michael Bell -- > Fine. Now the next stage of the design. > > My sorting tube has an internal diameter of 2.5 cms and the fan has an > internal diameter of 8 cms, and I want to connect them with an > inverted cone - actually an inverted pyramid because it will be > square-sided. Why for goodness sake ? Starting with two circles it's easier to make a cone. It will also be more efficient that some odd thing with squares crudely fitting circles. It could be reasonable with transition pieces for circle to square at each end but complicated to design and make. > So failing that, what I want to do is to do it in an energy efficient > way, and that means an evase. What angle should it be? There is plenty > of vertical space. What should the expansion angle be? 7 degrees included angle between the walls As a cone it will be 45 cms long Henry >> Fine. Now the next stage of the design. >> [quoted text clipped - 6 lines] > It will also be more efficient that some odd thing with squares crudely > fitting circles. I don't know how to do such a thing. Please explain how. Michael Bell -- >I wonder if anybody on this group can help me with this? > [quoted text clipped - 6 lines] >which are heavier = thicker, so it seems best to sort by falling speed >in air. Michael, Read all the helpful suggestions. As far as I can see, no-one has yet suggested a sideways air current. Since (as someone pointed out) the weight varies as the cube of the linear dimensions, and the cross-sectional area varies as the square, a bigger seed would be less deviated by a cross current than a smaller one, so the distance from the vertical axis at which the seed hits the ground should vary inversely as the size of the seed. You could try this quite easily, and (assuming it works) the apparatus should be quite portable. The cross-wind would have to be pretty constant, and the thing shielded from extraneous winds. The idea is quite reminiscent of the method used in a mass spectrometer, with an electromagnetic field acting as the "side wind". David SignatureDavid Littlewood >>I wonder if anybody on this group can help me with this? >> [quoted text clipped - 8 lines] >> > Michael, > Read all the helpful suggestions. As far as I can see, no-one has yet > suggested a sideways air current. > Since (as someone pointed out) the weight varies as the cube of the > linear dimensions, and the cross-sectional area varies as the square, a > bigger seed would be less deviated by a cross current than a smaller > one, so the distance from the vertical axis at which the seed hits the > ground should vary inversely as the size of the seed. > You could try this quite easily, and (assuming it works) the apparatus > should be quite portable. The cross-wind would have to be pretty > constant, and the thing shielded from extraneous winds. > The idea is quite reminiscent of the method used in a mass spectrometer, > with an electromagnetic field acting as the "side wind". > David I am aware of this idea, but I want something vertical so that I can hold it, and tip the cones in and get a result. I don't want something that needs to be levelled on a bench. Michael Bell -- >>>I wonder if anybody on this group can help me with this? >>> [quoted text clipped - 32 lines] > >Michael Bell Could you not hang it from say a tree branch and then weight it so it hangs level? Graham >>>>I wonder if anybody on this group can help me with this? >>>> [quoted text clipped - 32 lines] >> >>Michael Bell > Could you not hang it from say a tree branch and then weight it so it > hangs level? > Graham Not very portable, but possible. Michael Bell -- > I wonder if anybody on this group can help me with this? > > I want to find bigger alder seeds and breed from them to produce even > bigger alder sees. Yikes. I hope you're young. How many generations of tree breeding do you envisage? BugBear >> I wonder if anybody on this group can help me with this? >> >> I want to find bigger alder seeds and breed from them to produce even >> bigger alder sees. > Yikes. I hope you're young. > How many generations of tree breeding do you envisage? > BugBear Typo. It should have been "seeds". Yes, it's a hard one. Maybe beyond my time, though I plan to do it quicker than some think of. Michael Bell -- I may have misunderstood your proposed design, but surely you just need to blow air horizontally across a thin stream of falling seeds? No laminar flow issues, and not really any need for calculating - all seeds will fall through the same breeze. Adjust the wind speed or any baffles until light ones get blown to the side and heavy ones fall into your collector. If the proportion of small ones that get through is too highl, put the collection back in the top and do it again. This is basically how winnowing works, isn't it? Chas >I may have misunderstood your proposed design, but surely you just need to >blow air horizontally across a thin stream of falling seeds? No laminar flow [quoted text clipped - 7 lines] > >Chas Exactly what I suggested a day or two ago, but Michael didn't seem to like the idea. Seems a bloody sight simpler than all the other stuff being talked about. David SignatureDavid Littlewood > I may have misunderstood your proposed design, but surely you just need to > blow air horizontally across a thin stream of falling seeds? No laminar flow [quoted text clipped - 3 lines] > proportion of small ones that get through is too highl, put the collection > back in the top and do it again. > This is basically how winnowing works, isn't it? > Chas We were at cross purposes. Your idea is one that could work, but I have gone for a vertical design, where air is sucked upwards by a fan at the top, seed is put in half way up the duct, and only the heaviest falls down, the rest is blown out of the top through the fan. Michael Bell -- >> I may have misunderstood your proposed design, but surely you just need >> to [quoted text clipped - 18 lines] > > Michael Bell OK, this is basically the Millikan oil drop experiment to determine the charge of an electron, which I have done. In that case the electron has a predictable charge, the weight and air resistance of the oil drops are essentially constant and the force is provided by electrostatic plates - easy to get parallel (equivalent to laminar flow of your wind) and easy to adjust minutely. I think you will struggle with your design and I doubt very much if you can calculate the speeds required in advance, given all the variables that apply to wind resistance of real objects, but good luck. Charles Being unable to join in the genetics debate I'd like to ask a simple question. Why? In my experience Alder grow fast and die early. They also have little structural value, rot quickly and burn so fast as to be useless in an open fire or log-burner. About all I can see left is as Biomass fuel and my reading suggests that Willow and Hazel are better in most respects. puzzled and hoping for enlightenment.... SignatureRoland Craven Nr. Exeter, Devon, UK roland@petternut.co.uk www.petternut.co.uk > Being unable to join in the genetics debate I'd like to ask a simple > question. Why? [quoted text clipped - 3 lines] > About all I can see left is as Biomass fuel and my reading suggests that > Willow and Hazel are better in most respects. > puzzled and hoping for enlightenment.... It is true that some see alder as a competitor to willow, I hadn't heard of hazel, but it is also a fast-growing "weed tree". Alder burns well, so that is a GOOD, not a bad point, and kept under water, it doesn't rot and I think much of Amsterdam is built on pilings made of it. But I am interested in taking alder in a DIFFERENT direction. All organisms can be changed by selection, evolution is natural selection, and that is what makes alder (and all wild plants and animals) what they are today. Domesticated plants and animals have been changed by breeders and that is what I am trying to do. The odds are against my project, but I may find a Koh-i-Noor seed which changes everything. Michael Bell -- >> Being unable to join in the genetics debate I'd like to ask a simple >> question. Why? [quoted text clipped - 20 lines] > >Michael Bell I do understand you here, Michael. I was watching the RI Christmas lecture a few weeks ago, and was struck by the extent to which the early progenitors of today's cereal crops had been changed out of all recognition by selective breeding. Many, many generations of selective breeding, to be sure, but maybe with greater knowledge you can accelerate that. I certainly wish you well with it, anyway. Particularly struck by your comments on the wet rot resistance of alder. Now if you can breed it to produce good-sized strong timber of similar durability, that would be something. David SignatureDavid Littlewood >>> Being unable to join in the genetics debate I'd like to ask a simple >>> question. Why? [quoted text clipped - 27 lines] > breeding, to be sure, but maybe with greater knowledge you can > accelerate that. I certainly wish you well with it, anyway. > Particularly struck by your comments on the wet rot resistance of alder. > Now if you can breed it to produce good-sized strong timber of similar > durability, that would be something. > David It is already used as the body of electric guitars. You can't get cooler than that! Michael Bell -- |
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