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“Smart by Nature”

[Excerpt:] In nature, shape is cheaper than material. This has been shown a number of times and is manifested in the remarkably high performance, both absolute and specific, of biological materials (wood is one of the most efficient of materials; antler bone is tougher than any man-made ceramic composite) which is achieved not by the use of high performance components but by the degree of detail and competence in their design and construction.

Smart by Nature
http://www.bath.ac.uk/mech-eng/biomimetics/smartnat.htm

An essay from: Lightness — The Inevitable Renaissance of Minimum Energy Structures

There is a duality between engineering and nature which is based on minimum use of energy. This is because animals and plants, in order to survive in competition with each other, have evolved ways of living and reproducing using the least amount of resource. This involves efficiency both in metabolism and optimal apportionment of energy between the various functions of life. A similar situation obtains with engineering, where cost is usually the most significant parameter. It seems likely, then, that ideas from nature, suitably interpreted and implemented, could improve the energy efficiency of our engineering at many levels. This transfer of technology, variously called bionics, biomimetics or biognosis, should not be seen so much as a panacea for engineering problems as a portfolio of paradigms.

In nature, shape is cheaper than material. This has been shown a number of times and is manifested in the remarkably high performance, both absolute and specific, of biological materials (wood is one of the most efficient of materials; antler bone is tougher than any man-made ceramic composite) which is achieved not by the use of high performance components but by the degree of detail and competence in their design and construction. The implication is not only that animals and plants have to work hard to win the raw materials – sugars, amino acids, salts – from their environment, but that their control over the assembly and shaping of these materials is much more complete than ours. An essential part of this control is the cellular feed-back mechanisms which direct the accretion of material to places where it is most needed, resulting in adaptive structures. The shape of a tree is the history of the forces which were acting on it while it grew. These same sensory mechanisms, allied to a more mobile effector system as found in animals, lead on to structures whose lightness and apparent fragility are made robust by the ability to adapt shape and structure quickly to changing loads. This adaptiveness not only reduces the energy input into the production of the structure, but also allows it to adapt to changing forces and circumstances during its lifetime, many of which may be unpredictable. Such adaptiveness has also been called smart or intelligent behaviour.

The concept of Smart or Intelligent materials (and systems and structures) has been around for a number of years. A “smart” material (or system or structure – the one word takes all) interacts with its environment, responding to changes in various ways. A simple example is photochromic glass, darkening on exposure to light. In order to be responsive to its environment a material must have structure (for example, the molecular mechanism underlying photochromic glass) and in most instances is a system since it needs a receptor or range of receptors, a central processor which can differentiate between the inputs and integrate them into a single output, and an effector. This system could be considered as a material if it were integrated within a single lump of stuff (rather than having wires going from and to the central processor) and were being used or observed in a size range at least (somewhat arbitrarily) ten times larger than the size of the individual components. Smartness can be a simple response which follows on directly and inevitably from the stimulus; or the outcome of an if-then construct in which a decision is made based on balancing the information from two or more inputs; or the ability to learn, which is probably the smartest thing of all, since learning can lead to a patterned model of the world (the brain is “stored environment”) allowing informed prediction. It can be argued that the successful organism is the one which knows what is going to happen next and that prescience is more important than smartness, or at least subsumes it. How can smartness be implemented, and what might it do for technology? I think it’s worth first comparing the design philosophy of nature with that of an engineer. Consider a robot such as might be found in a factory. It is carefully designed so that the arms are of the correct length and stiffness for their purpose. The joints are carefully made and give the arm(s) well-defined arcs and planes of movement. Compare the animal equivalent, which has arms of undefined length and varying stiffness, joints with very well designed bearing surfaces, and arcs and planes of movement which are relatively vaguely defined. The skeleton is defined purely functionally and can have a relatively wide variety of shapes and still work properly. For instance, in learning to walk you have a general aim and make adjustments until you manage it. But everyone walks differently due to their individual technique and adaptations to their own particular design of skeleton. So the structure of a robot need be defined only in terms of its load bearing ability and the positions and places in which it needs to hold or place things. It is necessary to have very good bearings at the joints but the material and structure of the arms and other parts are far less critical. But there is no way the robot can tell where the end of its arm might be. It has to be taught by example. Move the bits of the robot to where you want them to be and let the robot remember how it did it. Such a concept would be far cheaper to produce. For “robot”, read “any sort of machine or structure”. The important point is that you don’t have to engineer every part of the structure to very high tolerance if the structure is smart and can learn how to cope functionally with what it is.

The concepts of robotics can be applied to buildings, making them mechanically adaptive. This is already done in a relatively primitive way to give some protection against earth movements. But a truly responsive building would be prestressed, converting compressive loads into tensile ones, gathering all the residual compressive loads into a single mast. It would then respond to changes in internal and external forces by adaptively changing its state of prestress, giving lightweight stability. The technology for implementing such designs is with us, at least in “bolt-on” mode. Piezoelectric elements can provide strain sensing and small-scale actuation, as can strain gauges and linear motors. Integration of input and output is a trivial problem with modern technology, although precisely what action might be taken in response to a given input is not always obvious.

Nature’s technology involves miniaturisation and integration. Sensing necessarily occurs at the molecular level. Sensitivity is much higher – in the campaniform sensillum of insects, for instance, nanometer displacements can be registered. The sensillum is integrated into the fibrous composite material which makes the exoskeleton of the insect in such a way that it can transmit displacements to the sensor cell, without compromising the mechanical continuity of the exoskeleton. This gives a model for strain sensors which could be built into a composite skin such as is used in fighter aircraft to form the basis of a health monitoring system or form part of a smart control and feedback system. The UK Defence community is also working on a reconfigurable aerofoil whose material is based on the design of the skin of the sea cucumber. This skin is a fibrous composite material (collagen in a mucopolysaccharide matrix) which can change its stiffness. Thus it can soften, change its shape, and stiffen again. The actuation system for the aerofoil could be based on another current project – worms. A gel inside a suitably engineered compliant container with properly designed fibre orientations in the wall. The gel can be stimulated chemically (or electrically or thermally), change its volume by absorbing a solvent, and change its shape as a function of the geometry of its enclosure. Quite large forces can be generated in this way (plants lift concrete slabs using the same mechanism), yet the specific gravity of the system is only 1.

The ultimate smart structure would design itself. Imagine a bridge which accretes material as vehicles move over it and it is blown by the wind. It detects the areas where it is overstretched (taking into account a suitable safety factor) and adds material until the deformation falls back within a prescribed limit. We have the technology to detect the overload, but lack the means to add material automatically. We are part-way there with Carolyn Dry’s self-repairing concrete structures, in which fractures cause reinforcing material to be released from embedded brittle containers and added to the structure. The ideal would be for the material to be added from an external source so that the structure was not compromised by having to contain its own salvation, necessarily reducing its load-bearing ability. Combine this with adaptive prestressing and the ability to remove material from areas which are underloaded, and we have a truly adaptive architecture. This approach would result in lighter and safer structures, since stress concentrations would never occur, and the safety factor could be reduced as the structure reached its design optimum – registered as a reduction in the rate of internal reorganisation. The paradigm is our own skeleton.

Nature is smart – are we smart enough to learn its lessons?

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8 Responses to “Smart by Nature”

  1. certainly seems like a better line of reasoning when looking at the structures in nature is to ask “how is this designed?” than to ask “how did this evolve?”
    in the first case, we can (and historically do, even when not asking this question) discover new and fascinating solutions to problems of how nature performs all of the functions that we find in living systems.

    in the second case, we find ourselves (ala Richard Dawkins) creating elaborate and convoluted imaginations for how things might have happened. all too often, (perhaps even without exception) we find ourselves in the same quandary as the novelist who is forced to abandon a story that has become hopelessly entangled with conflicting details.

  2. “wood is one of the most efficient of materials”

    Depends on the application. I built a wooden dock a few years ago that’s 100 feet long and has a 20 ton boat moored to it. It’s in inland waters but not really protected and gets brutally bashed by the weather and the big boat wakes. After 3 years it’s still here (I’m on the boat as I write this) and still quite intact with no sign of deterioration. Everyone told me it couldn’t be done out of wood. Piffle. Wood is a wonderful material for stuff like boats and docks. For outdoor applications one has to use pressure treated wood otherwise some species of fungus and/or bugs will eventually eat it. Plywood used in the weather must have all edges sealed with expoxy otherwise it absorbs water and expands with all kinds of nasty consequences. And of course you should put a good coat of combination wood paint/sealer on all surfaces. And for gosh sake nails are obsolete. Use screws for everything wooden. Care also needs to be taken with wet wood (which is how you usually get it from the lumberyard). It needs to dry some before being used and it needs to be carefully placed/stacked so it doesn’t warp while drying. I usually dry fresh wood for 24/48 hours before using it and turn it every 8 hours or so and keep weights on it so it doesn’t warp. The really neat thing about wood is the ease with which things built from it can be repaired and modified. It’s a very forgiving material and well suited to amateur construction projects.

  3. Go where the money is – as of November 22, Howard Hughes Medical Instistute announced grants of 10m over 3 years for graduate programs for 10 schools in competition with 132, where; “biomedical, physical, and computational sciences intersect.” say it aint so Joe, where you goin with that ‘DNA’ gun in your hand.

    UC Irvine is one of the fortunate repositories of the new paid for direction. Link for UCI here: http://www.ics.uci.edu/communi.....ress?id=35

    Design, engineering, and revolution go hand in hand in this information reformation of bio-engineered programs.

    The Dept Chair says, “What design principles control embryonic development so that it is extremely accurate, exploit rapid cell growth to repair and regenerate tissues but restrain it from becoming cancer, or regulate metabolism so that energy is consumed when it is needed and stored when it is not?’ These are basically engineering questions within the context of biology. And, as with many engineering questions, one needs mathematics to frame them, and computer power to investigate them.”

    An errant judge does not tell science where it will go.
    Scientist will follow the evidence or in this case the money.

    Is Dolly created or evolved? When babies are born in the future with a choice of eye colour – will they be ‘designer babies’? Or evolved babies?

  4. The good in this article: we have something to learn from the structure and composition of things in nature.

    The crappy in this article: it is schizophrenic.

    “There is a duality between engineering and nature which is based on minimum use of energy. This is because animals and plants, in order to survive in competition with each other, have evolved ways of living and reproducing using the least amount of resource.”

    “Minimum use of energy” good.
    “in order to survive in competition with each other, have evolved ways…” crappy.

    What?! Is this undirected evolution or directed evolution? What is “directed evolution”? It sounds like the plants and animals are “intelligently designing” THEMSELVES!

    But wait. “…antler bone is tougher than any man-made ceramic composite) which is achieved not by the use of high performance components but by the degree of detail and competence in their design and construction.”

    Design and construction? Those are words that can only accurately be used where something is well, “designed” and “constructed”, something that has complex specificity. Wait! That’s Intelligent Design.

    I mean, this is a good article where it touches on things that can actually be observed. It wastes enormous energy trying to couch its observations in terms of evolutionary logic.

  5. They should hire me to be their editor to get rid of the crappy.
    This is how the first two paragraphs SHOULD read.
    ….
    There is a duality between engineering and nature which is based on minimum use of energy. This is because animals and plants are designed to live and reproduce using the least amount of resource. This involves efficiency both in metabolism and optimal apportionment of energy between the various functions of life. A similar situation obtains with engineering, where cost is usually the most significant parameter. It seems likely, then, that ideas from nature, suitably interpreted and implemented, could improve the energy efficiency of our engineering at many levels. This transfer of technology, variously called bionics, biomimetics or biognosis, should not be seen so much as a panacea for engineering problems as a portfolio of paradigms.

    In nature, shape is cheaper than material. This has been shown a number of times and is manifested in the remarkably high performance, both absolute and specific, of biological materials (wood is one of the most efficient of materials; antler bone is tougher than any man-made ceramic composite) which is achieved not by the use of high performance components but by the degree of detail and competence in their design and construction. The implication is our engineering achievements are still far short of the intelligence designed into living systems. Living systems are designed with lightness and apparent fragility that are made robust by their structural ability to adapt shape and structure quickly to changing loads. This adaptiveness not only reduces the energy input into the production of the structure, but also allows it to adapt to changing forces and circumstances during its lifetime, many of which may be unpredictable. Such adaptiveness has also been called smart or intelligent behaviour.
    ….

    Subtle difference but, well… smarter and more intelligent.

  6. “wood is one of the most efficient of materials”

    For a look into the anatomy of wood species and the engineering characteristics of woods, I recommend R. Bruce Hoadley, of UMass-Amherst, published by Taunton.

    Wood is amazing. No doubt about it. Hats off to nature. But the most amazing thing is what intelligence does with it. Scot’s planks will last a long time because intelligence pressure-treated them with chemical salts and another intelligence applied them properly and will, no doubt, maintain them if necessary. As Scot pointed out, almost any species of untreated plank would disappear in short order no matter its hue, figure, shear strength, bending strength or tensile strength.

    A typical 1950s-era Doug Fir stud, one stud, will support an automobile if braced plumb. Hats off to nature and the compression strength of D-fir. A house framed up of such might easily last hundreds of years but that depends on the builder. If sited poorly, plated on grade, improperly flashed, subject to uneven roof loads, poorly braced and blocked, improperly fastened, improperly vapor-sealed, or any number of other things, those amazing tight-grained coniferous elements will soon be fodder for molds that are just as amazing as any wood.

    The essayist is apparently unacquainted with existing “truly responsive” wood structures. The Urnes stave church (c. 1150) in Sogn og Fjordane County, Norway, is not a tribute to wood but to engineering. Drive through Midwest farm country in America and look for old barns with straight ridges, true purlins and level stonework. Even if you build them perfectly plumb and level, they will sag because gravity never sleeps and wood fibers will deflect along their long axis. That is, unless your counter-loads balance perfectly and your joints move or stress-lock as called for. Now look at the neighbor’s once proud gambrel stable, which is melting into the sod. Wood is cool but not as cool as things happening inside the heads of Amish framers, English coopers, Chippendale masters and boatwrights. I definitely don’t favor the essayist’s “single mast” load compression scheme. Then you’ve got a single point load translated to what damn well better be bedrock and your central member is a throw of the dice. Some things better be rigid and some things better have a modulus of elasticity but I would spread the loads.

    The old ”dory” design in Newfoundland could almost be a deep, flat-bottomed canoe. But the physics have been honed to strict tolerances on the round, stuff that Kepler would figure out if he had enough coffee. It is unnerving to be pitching about off the bay in one of these things with a couple old guys, neither of whom can swim. Wouldn’t do a spot of good anyway. Water’s too cold. The wood is Labrador pine. You can write your initials on the transom with your thumbnail it’s so soft. You look at the waves sucking 20 feet down the sheer rock cliff just off from the gill nets and you know that one bump and you’re sleeping with Mr. Flounder. The bow man sets a jib and puts you into the wind so the nets can be hauled. It’s not the pine that’s amazing: it’s the white-headed old buzzard up in Notre Dame Bay that knew how to build this thing. The more cod you load in, the lower the gun’ls get. Thing is, the more swamped you are, the more impossible it is to sink the damned thing. It’s so counter-balanced that you can’t flip it without a crane and you can’t sink it without a ten-ton plunger. Them old Scandy’s & Irish & Scots are always thinking and not much of that thinking is about how marvelous northern white pine is.

  7. Who knew we had a couple of lumberphiles (pmob1 and DaveScot) in our midst?

  8. keiths,
    You wrote: “Who knew we had a couple of lumberphiles?”

    I did, but only because my thumb is so purple. I think Dave’s point was that most houses today are built with low-grade wood waste products and glue. Amazing. Ditto cabinets, which tend to be veneered compound board, with just the face frames and doors in good old solid wood. Personally, I hate sawing and lifting that stuff and it’s less durable and a few other things. I stick with the pile of cherry or walnut or maple, but efficient? NOT.

    Wood is stunning, but only because of design. How about Trex for the deck or Pergo for the floor? A big white oak truss beam is an awesome thing. But how about a ‘lam? Let’s say the idiot architect drank too much coffee and goofed the roof design real bad, like UN!! …believeable. And now you have to find a big 41 foot ridge beam to save his stupid ass plan. Well, just reach into your pocket and call your guy at the desk and custom-order it. Microlam, Parallam, whatever. Made out of junk wood and glue. Incredible.

    Furniture is often still all wood and generates amazing esthetics but it turns out that proportion is quite a bit more important than the wood itself. It’s almost like you’re dealing with Pythagorean ratios or the “universals” of philosophy. In some of the very spare styles, like Shaker, the real craft is the generation of space. Sometimes you can look at this as space-ing (of wood elements) but quite a bit of the time you’re working with air itself. The voids are dominant design elements as in sculpture or architecture. In tables, very small angle deviations or a minor, but regrettable router detail just wrecks the whole thing. Sometimes it’s not obvious why. There is a whole science behind the type and angle of leg tapers, for instance. Tiny gradient shift changes are to be avoided unless you’re experimenting. The wood guys have been keeping tabs on this stuff for a zillion years. You just keep your mouth shut and do what they say until you start to see it (if ever).

    This guy raves about the wonders of antler horn. Okay. But how about a 7mm Remington Mag at 500 yards? You’ve got about 2000 fps and you deliver about 1500 foot pounds of energy, all in a mere 1/3 ounce of lead. And now the antler bone is on the ground with the rest of it, and you better go gut it and haul it out of there before it gets dark.

    Most creation looks pretty designed to me, including wood. I guess you can argue it both ways. But humans? Debate over. Dead giveaway.