Crystolecular unit

From apm
Jump to: navigation, search
This article defines a novel term (that is hopefully sensibly chosen). The term is introduced to make a concept more concrete and understand its interrelationship with other topics related to atomically precise manufacturing. For details go to the page: Neologism.

This page is about small assemblies of crystolecules of a typical size scale of maybe about ~64nm (very crudely widely varying).
This page covers all suitable gemstone-like compounds used as base material. Not just ones with diamondoid structure.

Crystolecular elements are:

Crystolecular elements:

  • are typically often not disassemblable because they where partially fused together.
  • sometimes have enclosed movable elements

Here on this wiki the term "crystolecular element" will be used to refer to
functional components (structural or machine elements) that
may have any kind of suitable gemstones as base materials.

Examples of the diamondoid sub-class

For the subclass with diamond-like structure see: Diamondoid crystolecular machine element
And for specific examples of this subclass see:

A basic diamondoid sleeve bearings is a small diamondoid crystolecular machine element made out of two diamondoid crystolecules.

Machine elements (DMMEs)

Types

Bearings

DMME bearings exhibit superlubrication. In the case of diamondoid rotative bearings this looks like described here: E.Drexler's blog: Symmetric molecular bearings can exhibit low energy barriers that are insensitive to details of the potential energy function.

The occurring friction is orders of magnitude lower than the one occurring when liquid lubricants are used in macro or microscopic (non AP) bearings E.Drexler's blog: Phonon drag in sleeve bearings can be orders of magnitude smaller than viscous drag in liquids.

DMME bearings can be built such that the force between bearing and axle is anti-compressive further lowering dynamic drag but also lowering stiffness possibly down to zero. E.Drexler's blog: Bearings can be stable despite attractive interactions between their surfaces (related: levitation)

If badly chosen the combined symmetry of bearing and axle can create a bistable tristable or an other low symmetry configuration. This should usually be avoided. Some symmetry considerations can be found here: Zyvex; Ralph C. Merkle: A Proof About Molecular Bearings and iirc on the Nanoengineer-1 developer wiki which went missing. :(

A tutorial on bearing design can be found here: A Low-Friction Molecular Bearing Assembly Tutorial, v1

Friction elements

Interlocking teeth with low stiffness can snap back and thermalize energy. E.Drexler's blog: Softly supported sliding atoms can undergo abrupt transitions in energy This can serve as a break (analog to an electrical resistor in an electrical circuit)

One very interesting machine element design is the warp spring clutch. [1] google

Gears

Single rows of protruding atoms can be used as gear teeth. But a simple pair of inter-meshing straight bevel-gears has a lot higher bumpiness than well designed DMME bearings. This can be reduced by making the gears very slightly helical (e.g. through applied strain) so that simultaneous contacts have phase shifts thoroughly below the angle of a tooth. Such bump-smoothing-gears have not been designed and analyzed yet (2014) [Todo: example design]. Meshing pairs of unequal designed gears may help too.

Making the teeth bigger by using more but not much more than one atom row for a gear gives a lot of undisired "bumpiness".

Quite a bit bigger gears could use involute teeth like their macroscopic cousins. Involute teeth can be approximated by strained and or dislocation including diamondoid structures. Surface structure is best kept non-aligning. Friction prone passivations like a standard hydrogen passivation should be avoided. Graphite linings might be usable. It remains to be analyzed whether and if which advantages approximations of involute and other gear profiles provide. The effects on transmittable torque, axial pressure and so on are of interest.

Considerations about stiffness as in superlubrication for DMME bearings are equally relevant for grears [more details needed].

Fasteners

Details can be found on the locking mechanisms page.
Enclosed radicals could be used to make very compact reversible connectors (name suggestion: covaconns - for covalent connectors)

  • [Todo: note details about the expanding ridge joint]

Pumps

There is a model of a single atom neon pump which to some degree acts as a filter too. Positive displacement pumps like piston pumps scroll pumps or progressing cavity pumps have not yet been designed.

Others

  • Parts for the management of semi diamondoid structures - e.g. coil barrels - those are especially amenable for testing.
  • [Todo: telescoptc rods; joints; hinges .... ball joints -> issues lack of ball curvature?]

Sets

To be able to build the maximal amount of different microcomponents with the minimal amount of DMEs one needs to design/pick optimal sets of DMEs from a very large design space.

Minimal set of compatible DMMEs

In electric circuits there is one topological and three kinds of basic passive elements.
Adding an active switching element one can create a great class of circuits.
0) fork node; 1) capacitors; 2) inductors; 3) resistors

Those passive elements have a direct correspondences in rotative or reciprocating mechanics namely:
0) planetary or differential gearbox [*]; 1) springs; 2) inertial masses; 3) friction elements
[*] and analogons for reciprocating mechanics (see: Nanomechanic circuits)

But there are limits to the electric-mechanic analogy. Some mechanic elements often differ significantly from their electric counterparts in their qualitative behavior. Two examples of elements quite different in behaviour are:

  • transistors & locking pins
  • transformers & gearboxes

With creating a set of standard sizes of those elements and a modular building block system to put them together creating rather complex systems can be done in a much shorter time.
Like in electronics one can first create a schematics and subsequently the board.

To do: Create a minimal set of minimal sized DMMEs for rotative nanomechanics. Modular housing structures standard bearings and standard axle redirectioning are also needed.

To investigate: how can reciprocating mechanics be implemented considering the passivation bending issue

Structural elements (DMSEs)

An example of a diamondoid molecular structural element (DMSE). The bright red spots are open bonds.

There's the shape-lock-chain-core-reinforcement principle. For details see: Structural elements for nanofactories

DME Adapters

It makes sense to have for each standard DME no matter of which type an adapter to a "the" standard couplings on the transportation chains. Since adapters will be reusable for many cycles the necessary production capacity for part-A-adapters will be much smaller than the targeted production capacity for part-A-DMEs. Building (mechanosynthesizing) the adapters right on the transportation chain couplings avoids the necessity of adapters for adapters.

Connections at this level will mostly be sparse covalent reversible and for a bit bigger parts Van der Waals and shape locking.

Sets

  • standardised building block systems
  • housing structures
  • standard corner pieces connecting the various crystallographic planes
  • in edge passivation with hydrogen can be problematic
  • issue of non androgynous sinterfaces
  • brackets for sub bond length positioning [[2]]
  • standard pipe and channel segments - the passivation bending issue is of relevance

Molecular transport elements

Elements that create one dimensional structures for the logistic transport of different media are a bit of a cross between machine elements and structural elements.

data transmission

For transmission of data in Nanosystems polyyine rods where proposed. They constitute the thinnest physically possible rod manufacturable and consist out of sp hybridized carbon which must be mechanosynthesizable for their construction which goes beyond minimal necessary capabilities (sure?). Handling of sp carbon is involved in already analyzed tooltip chemistry though and thus likely to be available. Polyyne rods obviously are rather susceptible to radiation damage thus it might be wise to use chains of benzene rings which are more stable. With the first few additional ring widths the event of non self healing catastrophic damage becomes drastically more unlikely per unit of time. [Todo: calculate estimations] Still two of those ribbons like to fuse under UV irradiation (see: anthracene) Going to cyclohexan chains and bigger diamondoid rods makes the surface a lot more bumpy and the housings a lot more bulky.

  • parity bits and more elaborate (somewhat holographic) data redundancy
  • bit flip - tape rupture

energy transmission

For power transmission strained shell near cylindrical diamondoid axles are a good possibility reciprocative movement may be better for high power densities.

Heat transport

For thermal drain water works well because of its very high heat capacity. To drastically reduce friction one should pass it around enclosed in diamond pellets (capsule transport) to get it in either one needs to use very high pressure (sealing might be difficult; thermal conductance may suffer) or the insides are made hydrophobic by adding -OH instead of -H surface terminations. In the latter case mechanosynthetic oxygen placement capabilities are needed which go beyond minimal necessary capabilities. Pipes are easily creatable but work better at the macroscale. It may be possible to use the phase transition ice water to keep the factory at constant temperature but note that super-clean water (that occurs as waste see below) does not necessarily freeze when super-cooled and the melting point might be significantly altered in small possibly hydrophobic encapsulation.

raw material supply

For supply of solvated raw material the same method as for the cooling solvent can be used.

waste removal

A waste that always occurs at a low rate comes from oxidation of excess hydrogen - atomically clean water. Water can be drained via pipes or enclosed in pellets [more investigation of existing literature needed]

Beside that depending on how much self repair capability is included waste can be constituted out of shunned microcomponents because they are irreparable or likely to be broken or dirt contaminated. (see: "microcomponent tagging") or out of dysfunctional DMEs caused by assembly errors. ...

General properties of DMEs

To get a better picture how DMEs behave mechanically and in general how everything else behaves at this size range one can look at the scaling laws which describe how physical quantities scale with size.

DMEs with carbon, silicon carbide or silicon as core material can have internal structure like

Due to the lack of defects the ultimate tensile strength of larger DMEs lies above diamond of thermodynamic origin.

Strained shell structures

To form cylindrical or helical structures with high to maximal rotational symmetries for their size (good axles for superlubrication) one usually constructs wedge shaped segments and put them together until they naturally turn around 360 degree. Bending can be induced from internal structure or surface passivation (since passivation atoms haven't got the exact same bond length like the internal atoms, see: passivation bending issue). If 360° are exactly met the structures bending results from internal unstrained structure the whole structure is unstrained - a goal to aim for. If not bending to a strained shell is required. For thin tubes of high diameter a completely unstrained lattice of the used diamondoid material can be bent around. A note on bending tools can be found on the "mechanosynthesis" page.

Spheres are rather hard to approximate. [to investigate: feasability of ball joints]

When the gap between axle and sleeves is made bigger then interestingly it is possible to achieve negative pressures.
See: Negative pressure bearings.

VdW sticking

See: locking mechanisms
[Todo: add calculation of how much surface is needed to securely overcome the characteristic thermal energy (100kT?) -- to locking mechanisms?? -- techlevel I related too ...]
[Todo: link to force estimation]

Acceleration tolerance

[Todo: add calculation of a block on a neck model - for "intuitive" understanding]

When halving size mass shrinks eightfold (scaling laws) this leads to ...

high tolerance to accelerations (and possibly slow building speeds) may seduce one to build very filigree structures. Especially nanofactories will have lots of vacuum filled free space inside. Since the structures still can be crushed by external pinching forces one should - to avoid health hazards and waste production - always design with prevention measures for sharp edges and splinters in mind.

Design of MMEs / crystolecules

To this date (2015) most of the designed crystolecules where made with the software nanoengineer-1 When designing DMEs some things have to be taken care of. See: Design of Crystolecules

Related

Retrieved from "http://apm.bplaced.net/w/index.php?title=Crystolecular_unit&oldid=12628"