Yup. It's about the shashdot summary which sucks and completely misses the point. The press release focuses on the differences in the chemical composition of the hydrated cement (chiefly the presence of aluminium atoms in the Roman cement) and how those differences may affect durability.
Roman works relied strictly on compression (arches and domes are good examples). There is no doubt that compression works can be more durable than tension structures because by the nature of the beast they require much more material to build. Because of this, they have much more material to wear off (redundancy) and so they can better resist the passage of time (and erosion).
Of course, as in everything, there are tradeoffs. One of them being the shear mass of materials required for construction. Engineering is about efficiency, and so for a structure of a lifespan of 50 years (typical design lifespan) roman-style strucures would be way over-engineered. Not only in terms of cost to build but in terms of energy consumption of the process. You are also limited in the freespan of a bridge you can build this way. Imagine the size of the arch that would be required to match modern suspended bridges spans... and the corresponding amount of rock and/or concrete needed and you start getting an idea of what efficiency means in those terms. Some things would just be impossible to build the roman way.
Of course, if one of your key requirement is 2000+ years design lifespan, then using a compression design the roman way does make sense for many things. It's all about the design objectives.
From the headline one would think that this is the "secret ingredient" to the Roman concrete: "The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together"
However, this is pretty much how portland cement (the modern binder in concrete) reacts with water to form the concrete with the agregate. Reading the article, however this is what matters:
"One is the kind of glue that binds the concrete’s components together. In concrete made with Portland cement this is a compound of calcium, silicates, and hydrates (C-S-H). Roman concrete produces a significantly different compound, with added aluminum and less silicon. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder."
"At ALS beamlines 5.3.2.1 and 5.3.2.2, x-ray spectroscopy showed that the specific way the aluminum substitutes for silicon in the C-A-S-H may be the key to the cohesion and stability of the seawater concrete."
"Another striking contribution of the Monteiro team concerns the hydration products in concrete. In theory, C-S-H in concrete made with Portland cement resembles a combination of naturally occurring layered minerals, called tobermorite and jennite. Unfortunately these ideal crystalline structures are nowhere to be found in conventional modern concrete."
"Tobermorite does occur in the mortar of ancient seawater concrete, however. High-pressure x-ray diffraction experiments at ALS beamline 12.2.2 measured its mechanical properties and, for the first time, clarified the role of aluminum in its crystal lattice. Al-tobermorite (Al for aluminum) has a greater stiffness than poorly crystalline C-A-S-H and provides a model for concrete strength and durability in the future."
So basically, there is alimunium in the crystaline structure of Roman cement that contributes to the differences in performance over time (not raw strength). Another factor that may impact durability that is not covered here but that civil engineers will know well is the fact that modern cements are more alkaline than even early Portland Cement productions. As a result, they tend to react with the silicates in the aggregates of the cement (phenomenon known as alkali-aggregate reaction). If you see concrete with cracks that look wet even when it's not raining, that's a symptom of this effect. The reaction with the aggregates causes an expansion within the concrete which builds ups stresses locally and result in those cracks, with obviously unfortunate effects on the longevity of concrete structures.
Even without prestressing, (which reinforced concrete does allow) reinforcement provides additional tensile strength. Concrete's tensile strength is no more than 10% of its compressive strength which means it's nothing to write home about. You can get reinforcement from fibres (which is why the ancients would add straw to clay to make bricks).
The point is that while pretensioning does give you added tensile resistance (by converting the inital tension to a reduction of the pre-imposed compression), reinforced concrete does not require pre-tensioning to reinforce concrete in tension, and in most cases just the presence of rebar is enough to provide the required tensile resistance. Pretensioning will be used when larger spans (and therefore larger tensile stresses in some parts of the beams) are required.
Actually, I'd say unless you have a government bent on controlling the news, state media usually provides the most neutral less "hyped" information. I know in the US it's all about "nothing should be state owned" but beyond the rethoric in many instances state media have provided the best quality TV, certainly in terms of information. Too much of private TV news is entertainment. The CNNisation of news is a terrible tragedy.
I cannot say what the situation was in Greece, but if it is similar to what I have experienced when I have been in Western Europe, greeks have probably lost their best source of news.
I'm still running Debian on 64 MB of RAM. With Xwindows and icewm. I can even browse the interwebs for a while with firefox until I hit a page with javascript requirements that beat the OS requirements. Sadly that is becoming the norm (I'm looking at you gmail)
I don't think that anthropology deals much with fossils anyways. I don't know how long it takes for remains to fossilize, but I'd be willing to bet that it takes more than the few hundred millenia associated with ancient human studies. Anthropology deals more with actual bones than fossils, though even then, wood is probably usually one of the first casualties of time.
Well, if my name were "Everyone" cause my grandma uses it. Well, actually I got my dad to use it, but if my grandma lived and had a computer, I would have hooked her too.
It works with GoogleTalk accounts too.
Anyways, I use it. and THAT should be enough for the world.
Don't forget that the government of Extremadura is not going into this blindly. They've had their own distro (Linex) since the early 2000s, and already converted a number of computers and basically Linuxified their schools. They have a decade of experience to draw on and probably have estimated the cost of migration (or not migrating) based on it.
And I would agree with you, I have old crap hardware running Linux and can still run the latest software on it (slowly). I get the latest security patches, but if the software I need runs on that hardware, Linux is pretty much what lets me use it in an up-to-date way. Windows 98 is incompatible with most current software yet is the latest version of Windows that will run on the old clunkers. One of the high costs of Windows is having to keep upgrading your hardware needlessly if you want to keep up with the security patches (a must on a connected machine).
Just a quick search suggests that SysGobEx is actually the strategic plan to implement opensource in government. Extremadura actually had sponsored a linux distro called Linex (still being maintained as per distrowatch) back in the early 2000s. I think the headline submission text needs a revision.
Actually Extremadura did not need the crisis for this specific endeavour. Maybe only to complete the migration. Extremadura has had its own distro since the early 2000s (called Linex). It was one of the first state sponsored distros out there. I don't know what the state of the migration was before this latest push, but it is certainly not a new initiative. They do seem to have created a new distro though. I'll have to see how it differs from Linex.
The crisis certainly did provide an additional motivation to complete the migration, for sure. But Extremadura was already a pretty poor place even before which had prompted its original plans.
Actually Extremadura did not need the crisis for this. It has had its own distro since about 2001 (called Linex). It was one of the first state sponsored distros out there. I don't know what the state of the migration was, but it is not a new initiative. They do seem to have created a new distro though. I'll have to see how it differs from Linex. It's probably more about completing the migration that had started some time back and would have been delayed by some leftover compatibility issues.
The crisis certainly did provide an additional motivation for sure. But Extremadura was already a pretty poor place even before which had prompted its original plans.
Actually, Coelurosauria are not the only feathered dinos anymore. I think they have found feather evidence on Carnosaurs as well making pretty much all theropods likely to have been feathered.
And let's not forget the "hairy" tail fans of the Psittacosaurus which certainly indicate that even ornithischians had non-scaly skin covering. Actually there is even more evidence of proto feather like structures in both ornithischians and saurischians.
All in all one can't discount some sort of skin covering. That being said, I seem to recall reading somewhere that many animals that have coloured covering over their skin (scale, feathers, or hair) often have corresponding matching colouring (or at leasat pattern) on the skin itself. It wouldn't be a complete waste of time in any case.
P.S. I am not an expert either, but David Hone (of archosaur musings is) is, so you can find a bit of good info on his website.
I completely agree. Prefabricated components are the way to go. Other than the ease of construction, they will allow more material to be used from an earlier construction in a new one, thus reducing the energy and material cost of new constructions. If anything LEEDs will encourage the trend towards modularity.
Actually 3D printed structures are probably a bad idea in general, unless it is meant to be a "national" building that will be maintained and last for ideally hundreds if not thousands of years. A 3D printed building is not likely to be able to use materials from pre-existing structures, and whatever is printed is unlikely to be resuable at the end of the structure's lifespan. There is much more future in the design of Leg-like construction modules that would make it easy to assemble and disassemble structural compnents.
An added disadvanted of the printed building is that I see it being difficult to actually print "reinforced" concrete this way. I'm not sure a two storey building would be safe, let alone a multistorey building. Very short span single storey buildings seems to be as much as you can get out of it. It's good for sheds, but not much else. But really the lack of reusability of components is its greatest Achiles heel going on.
In Canda, the main funding agency gives you points for developing HQP (highly qualified personel). If you don't give the credit to your students you're less likely to get future funding because you're failing in your main task. It's a strong incentive to give credit where credit is due. I imagine it must be similar in other jurisdictions, but of course I don't know that it is.
I would say a government has more incentive than any private entity in maintaining roads. What incentive would a private contractor have in maintining it right? If it gets paid a fixed rate for "operation" then the more skimping on quality means more profit. If it gets paid per "calls" to fix things then the more it gets called the better ensuring poor quality worksmanship. Only government has any incentive in proper maintenance as a well maintained road means less costs in the long term to fix it, and less liability is someone is injured because of improper maintenance.
That's the problem with Apple. You don't buy an Apple device. You buy the right to USE one of THEIR devices. It has always been so, and the reason I was never tempted to buy anything Apple.
Seriously, how does using MS Office not result in performance impairment frustration and aggravation. Most of my students issues stem directly from use of MS Office. That's all they know, but it's still their main source of aggravation and frustration. From very poor iteration procedures (seriously, you can't force recalculation of cells past a certain point once Excel has decided that it's just done, however many times you try to recalculate), to handling in Word of figures, arbitrary variables (for template automation) to little things like an actually usable mail-merge, or compatibility with older.doc formats MS Office just sucks. The article is disengenuous at best. MS Office has nothing (useful) that OpenOffice doesn't have, and lots of things that it's missing.
This is my second "Sci-Fi tech could become reality in the none too distant future" of the last 20 minutes. (The first one being Sundiveresque http://www.eurekalert.org/pub_releases/2012-11/uoi-plt111312.php). If I keep reading, I might find out someone about to make a working version of a warp drive.
Now THAT would be bold. Laser cooled, laser propulsion manned solar exploration vehicle. Until they can match David Brin's dream, nothing about solar exploration will feel "bold" to me. Sigh. I'm spoiled.
Slashdot Mirror
From the press release: "The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder."
Now, if they could only make it transparent...
Yup. It's about the shashdot summary which sucks and completely misses the point. The press release focuses on the differences in the chemical composition of the hydrated cement (chiefly the presence of aluminium atoms in the Roman cement) and how those differences may affect durability.
Roman works relied strictly on compression (arches and domes are good examples). There is no doubt that compression works can be more durable than tension structures because by the nature of the beast they require much more material to build. Because of this, they have much more material to wear off (redundancy) and so they can better resist the passage of time (and erosion).
Of course, as in everything, there are tradeoffs. One of them being the shear mass of materials required for construction. Engineering is about efficiency, and so for a structure of a lifespan of 50 years (typical design lifespan) roman-style strucures would be way over-engineered. Not only in terms of cost to build but in terms of energy consumption of the process. You are also limited in the freespan of a bridge you can build this way. Imagine the size of the arch that would be required to match modern suspended bridges spans... and the corresponding amount of rock and/or concrete needed and you start getting an idea of what efficiency means in those terms. Some things would just be impossible to build the roman way.
Of course, if one of your key requirement is 2000+ years design lifespan, then using a compression design the roman way does make sense for many things. It's all about the design objectives.
From the headline one would think that this is the "secret ingredient" to the Roman concrete: "The lime was hydrated — incorporating water molecules into its structure — and reacted with the ash to cement the whole mixture together"
However, this is pretty much how portland cement (the modern binder in concrete) reacts with water to form the concrete with the agregate. Reading the article, however this is what matters:
"One is the kind of glue that binds the concrete’s components together. In concrete made with Portland cement this is a compound of calcium, silicates, and hydrates (C-S-H). Roman concrete produces a significantly different compound, with added aluminum and less silicon. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder."
"At ALS beamlines 5.3.2.1 and 5.3.2.2, x-ray spectroscopy showed that the specific way the aluminum substitutes for silicon in the C-A-S-H may be the key to the cohesion and stability of the seawater concrete."
"Another striking contribution of the Monteiro team concerns the hydration products in concrete. In theory, C-S-H in concrete made with Portland cement resembles a combination of naturally occurring layered minerals, called tobermorite and jennite. Unfortunately these ideal crystalline structures are nowhere to be found in conventional modern concrete."
"Tobermorite does occur in the mortar of ancient seawater concrete, however. High-pressure x-ray diffraction experiments at ALS beamline 12.2.2 measured its mechanical properties and, for the first time, clarified the role of aluminum in its crystal lattice. Al-tobermorite (Al for aluminum) has a greater stiffness than poorly crystalline C-A-S-H and provides a model for concrete strength and durability in the future."
So basically, there is alimunium in the crystaline structure of Roman cement that contributes to the differences in performance over time (not raw strength). Another factor that may impact durability that is not covered here but that civil engineers will know well is the fact that modern cements are more alkaline than even early Portland Cement productions. As a result, they tend to react with the silicates in the aggregates of the cement (phenomenon known as alkali-aggregate reaction). If you see concrete with cracks that look wet even when it's not raining, that's a symptom of this effect. The reaction with the aggregates causes an expansion within the concrete which builds ups stresses locally and result in those cracks, with obviously unfortunate effects on the longevity of concrete structures.
Even without prestressing, (which reinforced concrete does allow) reinforcement provides additional tensile strength. Concrete's tensile strength is no more than 10% of its compressive strength which means it's nothing to write home about. You can get reinforcement from fibres (which is why the ancients would add straw to clay to make bricks).
The point is that while pretensioning does give you added tensile resistance (by converting the inital tension to a reduction of the pre-imposed compression), reinforced concrete does not require pre-tensioning to reinforce concrete in tension, and in most cases just the presence of rebar is enough to provide the required tensile resistance. Pretensioning will be used when larger spans (and therefore larger tensile stresses in some parts of the beams) are required.
Actually, I'd say unless you have a government bent on controlling the news, state media usually provides the most neutral less "hyped" information. I know in the US it's all about "nothing should be state owned" but beyond the rethoric in many instances state media have provided the best quality TV, certainly in terms of information. Too much of private TV news is entertainment. The CNNisation of news is a terrible tragedy.
I cannot say what the situation was in Greece, but if it is similar to what I have experienced when I have been in Western Europe, greeks have probably lost their best source of news.
I'm still running Debian on 64 MB of RAM. With Xwindows and icewm. I can even browse the interwebs for a while with firefox until I hit a page with javascript requirements that beat the OS requirements. Sadly that is becoming the norm (I'm looking at you gmail)
I don't think that anthropology deals much with fossils anyways. I don't know how long it takes for remains to fossilize, but I'd be willing to bet that it takes more than the few hundred millenia associated with ancient human studies. Anthropology deals more with actual bones than fossils, though even then, wood is probably usually one of the first casualties of time.
I know I knew the answer to this one. But I forgot.
Pidgin!
Well, if my name were "Everyone" cause my grandma uses it. Well, actually I got my dad to use it, but if my grandma lived and had a computer, I would have hooked her too.
It works with GoogleTalk accounts too.
Anyways, I use it. and THAT should be enough for the world.
Don't forget that the government of Extremadura is not going into this blindly. They've had their own distro (Linex) since the early 2000s, and already converted a number of computers and basically Linuxified their schools. They have a decade of experience to draw on and probably have estimated the cost of migration (or not migrating) based on it.
And I would agree with you, I have old crap hardware running Linux and can still run the latest software on it (slowly). I get the latest security patches, but if the software I need runs on that hardware, Linux is pretty much what lets me use it in an up-to-date way. Windows 98 is incompatible with most current software yet is the latest version of Windows that will run on the old clunkers. One of the high costs of Windows is having to keep upgrading your hardware needlessly if you want to keep up with the security patches (a must on a connected machine).
Just a quick search suggests that SysGobEx is actually the strategic plan to implement opensource in government. Extremadura actually had sponsored a linux distro called Linex (still being maintained as per distrowatch) back in the early 2000s. I think the headline submission text needs a revision.
Actually Extremadura did not need the crisis for this specific endeavour. Maybe only to complete the migration. Extremadura has had its own distro since the early 2000s (called Linex). It was one of the first state sponsored distros out there. I don't know what the state of the migration was before this latest push, but it is certainly not a new initiative. They do seem to have created a new distro though. I'll have to see how it differs from Linex.
The crisis certainly did provide an additional motivation to complete the migration, for sure. But Extremadura was already a pretty poor place even before which had prompted its original plans.
http://distrowatch.com/table.php?distribution=linex
http://www.linuxjournal.com/article/7908
http://en.wikipedia.org/wiki/GnuLinEx
Actually Extremadura did not need the crisis for this. It has had its own distro since about 2001 (called Linex). It was one of the first state sponsored distros out there. I don't know what the state of the migration was, but it is not a new initiative. They do seem to have created a new distro though. I'll have to see how it differs from Linex. It's probably more about completing the migration that had started some time back and would have been delayed by some leftover compatibility issues.
The crisis certainly did provide an additional motivation for sure. But Extremadura was already a pretty poor place even before which had prompted its original plans.
http://distrowatch.com/table.php?distribution=linex
http://www.linuxjournal.com/article/7908
http://en.wikipedia.org/wiki/GnuLinEx
Actually, Coelurosauria are not the only feathered dinos anymore. I think they have found feather evidence on Carnosaurs as well making pretty much all theropods likely to have been feathered.
And let's not forget the "hairy" tail fans of the Psittacosaurus which certainly indicate that even ornithischians had non-scaly skin covering. Actually there is even more evidence of proto feather like structures in both ornithischians and saurischians.
http://archosaurmusings.wordpress.com/2009/03/19/blah-blah-feathered-ornithischians-yawn/
All in all one can't discount some sort of skin covering. That being said, I seem to recall reading somewhere that many animals that have coloured covering over their skin (scale, feathers, or hair) often have corresponding matching colouring (or at leasat pattern) on the skin itself. It wouldn't be a complete waste of time in any case.
P.S. I am not an expert either, but David Hone (of archosaur musings is) is, so you can find a bit of good info on his website.
Definitely faster than PDF plugin. I've been using the pdf.js plugin since it first appeared. I'd never go back to the plugin.
I completely agree. Prefabricated components are the way to go. Other than the ease of construction, they will allow more material to be used from an earlier construction in a new one, thus reducing the energy and material cost of new constructions. If anything LEEDs will encourage the trend towards modularity.
Actually 3D printed structures are probably a bad idea in general, unless it is meant to be a "national" building that will be maintained and last for ideally hundreds if not thousands of years. A 3D printed building is not likely to be able to use materials from pre-existing structures, and whatever is printed is unlikely to be resuable at the end of the structure's lifespan. There is much more future in the design of Leg-like construction modules that would make it easy to assemble and disassemble structural compnents.
An added disadvanted of the printed building is that I see it being difficult to actually print "reinforced" concrete this way. I'm not sure a two storey building would be safe, let alone a multistorey building. Very short span single storey buildings seems to be as much as you can get out of it. It's good for sheds, but not much else. But really the lack of reusability of components is its greatest Achiles heel going on.
In Canda, the main funding agency gives you points for developing HQP (highly qualified personel). If you don't give the credit to your students you're less likely to get future funding because you're failing in your main task. It's a strong incentive to give credit where credit is due. I imagine it must be similar in other jurisdictions, but of course I don't know that it is.
I would say a government has more incentive than any private entity in maintaining roads. What incentive would a private contractor have in maintining it right? If it gets paid a fixed rate for "operation" then the more skimping on quality means more profit. If it gets paid per "calls" to fix things then the more it gets called the better ensuring poor quality worksmanship. Only government has any incentive in proper maintenance as a well maintained road means less costs in the long term to fix it, and less liability is someone is injured because of improper maintenance.
That's the problem with Apple. You don't buy an Apple device. You buy the right to USE one of THEIR devices. It has always been so, and the reason I was never tempted to buy anything Apple.
Seriously, how does using MS Office not result in performance impairment frustration and aggravation. Most of my students issues stem directly from use of MS Office. That's all they know, but it's still their main source of aggravation and frustration. From very poor iteration procedures (seriously, you can't force recalculation of cells past a certain point once Excel has decided that it's just done, however many times you try to recalculate), to handling in Word of figures, arbitrary variables (for template automation) to little things like an actually usable mail-merge, or compatibility with older .doc formats MS Office just sucks. The article is disengenuous at best. MS Office has nothing (useful) that OpenOffice doesn't have, and lots of things that it's missing.
Tube Babies coming soon to a lab near you.
This is my second "Sci-Fi tech could become reality in the none too distant future" of the last 20 minutes. (The first one being Sundiveresque http://www.eurekalert.org/pub_releases/2012-11/uoi-plt111312.php). If I keep reading, I might find out someone about to make a working version of a warp drive.
Good Times!
[forgot to login in my prev. post]
And air pressure storage is notoriously inefficient. How does it compare to fuel cells though?
Now THAT would be bold. Laser cooled, laser propulsion manned solar exploration vehicle. Until they can match David Brin's dream, nothing about solar exploration will feel "bold" to me. Sigh. I'm spoiled.