
	Where results make sense

Topic: Aperiodic

In the News (Mon 28 May 12)

EXECUTIVE POWER

Iran

ANALYSIS

Pakistan

Family compact

	Data communication system with prioritized periodic and aperiodic messages - Patent 4987571
		An arrangement is devised whereby channel access may be prioritized as between periodic and aperiodic messages by advantageously utilizing the occurrence of these microslots so as to give priority to the former while completely eliminating collisions therebetween and, at the same time, optimally controlling the efficiency of the system as a whole.
		For aperiodic message, having a further requirement is imposed, namely, that there be two consecutive microslot showing a not busy status immediately prior to the start of the transmission of the message.
		Further, the aperiodic messages are scheduled in a manner wherein the gaps that would otherwise obtain between the occurrence of messages on the inbound channel are effectively reduced to thereby increase the optimum efficiency of the system as a whole.
	www.freepatentsonline.com /4987571.html (4426 words)

	Wang tile - Wikipedia, the free encyclopedia
		However, in 1966 Robert Berger proved Wang's conjecture was wrong.
		He presented a set of Wang tiles that could only tile the plane aperiodically.
		In this case, traditional aperiodic tilings would show their very regular structure; much less constrained sets that guarantee at least two tile choices for any two given side colors are common because tileability is easily ensured and each tile can be selected pseudorandomly.
	en.wikipedia.org /?title=Wang_tile (715 words)

	Wang tile - Wikipedia, the free encyclopedia
		This meant it could fill the plane without holes, but the tiling couldn't be a simple repetition of a finite pattern.
		For example, the set of 13 tiles given above is an aperiodic set published by Karel Culik.
		Wang tiles have recently become a popular tool for procedural synthesis of textures, heightfields, and other large and nonrepeating bidimensional data sets; a small set of precomputed or hand-made source tiles can be assembled very cheaply without too obvious repetitions and without periodicity.
	www.wikipedia.org /wiki/Wang_tile (715 words)

	Cellular Automata - Definitions of "Cellular Automata"
		The word "cellular" does not immediately suggest a system of cells where all the cells are necessarily identical - and consequently its current technical use is misleading and counter-intuitive.
		The non-uniform and aperiodic systems under discussion share so much with cellular automata that it makes little sense to place them in a separate category.
		Aperiodic tesselations are not limited to Penrose-like structures - and may gain in significance due to natural occurrence.
	www.cell-auto.com /definition/index.html (668 words)

	fourier spectrum
		Shortly, the sine wave is continiuous and periodic but its spectrum is aperiodic and discrete.
		As the signal becomes aperiodic, when you try to "construct" it using periodic sinusoids, you need to have infinite signals upto infinite frequency (there are exceptions!).
		that fourier spectrum for aperiodic signals are discrete or continuous depends on the form of input signal.
	www.edaboard.com /ftopic93908.html (599 words)

	Aperiodic Tilings
		Radial and spiral tilings are aperiodic, for example.
		All known aperiodic tilings are based on shapes that can also tile the plane periodically.
		Although aperiodic tilings are not periodic, all known examples have profound long-range order.
	www.uwgb.edu /dutchs/symmetry/aperiod.htm (967 words)

	Aperiodic Tilings
		The first known aperiodic set was developed by Berger, and consisted of 20426 tile shapes(!), although he soon reduced this to 104 tiles.
		We also saw that at each stage of the construction process there is a great deal of freedom, partly because of the symmetries of the individual tiles under rotation and reflection, and also because the inflated tiles can generally de partitioned into the basis tiles in multiple distinct ways.
		In fact, it's not much of an exaggeration to say that every living creature is an aperiodic tiling of cells, produced by a two-phase process of uniform growth alternating with sub-divisions.
	www.mathpages.com /home/kmath540/kmath540.htm (1801 words)

	The Geometry Junkyard: Tilings
		An aperiodic set of Wang cubes, J. Culik and Kari describe how to increase the dimension of sets of aperiodic tilings, turning a 13-square set of tiles into a 21-cube set.
		Aperiodic space-filling tiles: John Conway describes a way of glueing two prisms together to form a shape that tiles space only aperiodically.
		In these aperiodic tilings (generated by a substitution system involving similar triangles) vertices are connected by paths almost as good as the Euclidean straight-line distance.
	www.ics.uci.edu /~eppstein/junkyard/tiling.html (1767 words)

	Title page for ETD etd-06172003-122153 (Site not responding. Last check: 2007-10-30)
		Measurements of the vortical inflow to the cascade produced by the generators and of the mean blade loading at the mid span are presented.
		The periodic and aperiodic behavior of the tip leakage flow downstream of the cascade, produced by this vortical disturbance, is also presented using phase and time averaged 3-component turbulence and pressure fluctuation measurements.
		The aperiodic fluctuation, containing most of the turbulence energy, is found appearing to be organized structures in large scale, and making the estimated instantaneous velocity field significantly different from the phase averaged periodic velocity field.
	scholar.lib.vt.edu /theses/available/etd-06172003-122153 (584 words)

	Electronic Structure of Quasicrystals
		They were able to track a single electronic state in both the aperiodic and periodic directions, showing that the same electronic state in the quasicrystal displayed both periodic and aperiodic character.
		They also noted three important similarities to the band structure of ordinary metals: Their work shows clear evidence of delocalized states (i.e., the electrons are not all confined to localized groups that move around a small cluster of atomic nuclei, as was predicted).
		That these features are related to the aperiodic order is evidenced by the fact that the band structure reflected the ten-fold structure of the aperiodic crystal plane.
	www-als.lbl.gov /als/science/sci_archive/quasicrystals.html (941 words)

	RPG Diffusor Systems
		Aperiodic modulation of a single asymmetric base shape allows infinite, seamless tiling and unlimited shapes are possible with different tiling patterns.
		This is possible, because the asymmetric central shape, determined by the architect or acoustician, morphs to identical sides, which have a zero gradient allowing adjacent tiles to seamless transition without discontinuity in any orientation (middle) forming a larger aperiodic array (bottom 4x4 array).
		The performance of the aperiodic array is similar to that of one of the acoustically optimized canopy elements.
	www.rpginc.com /products/bicubic/index.htm (671 words)

	Moiré patterns between aperiodic layers: quantitative analysis and synthesis (Site not responding. Last check: 2007-10-30)
		Moiré effects that occur in the superposition of aperiodic layers such as random dot screens are known as Glass patterns.
		Unlike classical moiré effects between periodic layers, which are periodically repeated throughout the superposition, a Glass pattern is concentrated around a certain point in the superposition, and farther away from this point it fades out and disappears.
		I show that Glass patterns between aperiodic layers can be analyzed by using an extension of the Fourier-based theory that governs the classical moiré patterns between periodic layers.
	diwww.epfl.ch /w3lsp/publications/moire/mpbalqaas.html (163 words)

	Chunky Kibbles's Final Year Project
		Implementing aperiodic servers in RT-Linux The aim of the project is to implement the Deferrable Server and Sporadic Server, two aperiodic server mechanisms, as additional scheduling policies in RT-Linux.
		Aperiodic [or Sporadic], where the system wasn't necessarily expecting it, but now must deal with the task.
		That's not to say it's not a cool toy that is of genuine use to you as a punter [although I wouldn't recommend it server side], but it isn't something you should be using and saying that your computer has real-time performance.
	www.icculus.org /~chunky/project (1288 words)

	Aperiodic Tiling, Penrose Tiling and the Generation of Architectural Forms from the book Nexus II: Architecture and ... (Site not responding. Last check: 2007-10-30)
		Aperiodic Tiling, Penrose Tiling and the Generation of Architectural Forms from the book Nexus II: Architecture and Mathematics
		The newly completed Storey Hall is literally covered in a particular set of giant, aperiodic tiles that were discovered by Roger Penrose in the 1970's and have since become known as Penrose tiles.
		The purpose of this binary analysis is not to critique Storey Hall or its use of aperiodic tiling but to use ARM's design as a catalyst for taking the first few steps in a greater analysis of Penrose tiling in the context of architectural form generation."
	www.leonet.it /culture/nexus/98/Ostwald.html (333 words)

	North Creek Music's new MAPD driver loading
		Aperiodic Damping of Acoustic Suspension systems with Qtc of above 1.1 is a cure for both the ringing and the "character", as Aperiodic Damping eliminates the ringing and adjusts the effective Q of the system.
		The aperiodic damping for the woofers is provided by a single Scan Speak Scan-Vent adjoining the first, 8.34 liter section to the second, 25 liter section.
		Aperiodically coupling into the second chamber drops the Qm much lower, to about 5.0 (hence the term "Progressive Damping"), and also lowers the system resonance frequency slightly.
	www.northcreekmusic.com /MAPD1.htm (1073 words)

	sam.ufm Helpfile
		The "Frame" mode is intended to be used with Gradient for Aperiodic Tiling IandII.
		These colorings can be used to frame the tiles produced with the transoforms Aperiodic Tiling I, III and IV and Aperiodic Tiling II.
		Note about Gradient for Aperiodic Tiling I and II : "Trapezoid" and "Rhombus" are to be used with Aperiodic Tiling I and "L" with Aperiodic Tiling II.
	www.p-gallery.net /help/aperiodic.htm (501 words)

	Institutional Research Plan A - 8. Structure and Electronic States of Solids
		X-ray diffraction: The structure analysis will be based on our original software JANA which is currently one of the leading systems in the field of the structure analysis of aperiodic and complicated periodic crystals.
		The first project is to develop data collection and processing software for handling the diffraction patterns directly in the superspace, with possibility of measurement of samples affected by twinning.
		The ambition of all these projects is to develop a general system working for three-dimensional as well as multidimensional structures, single domain, multidomain or intergrowth crystals, single crystals or powders, nuclear or magnetic structures, with a unique interface and dirrect support of difractometer output.
	www.fzu.cz /research/cond_systA8.html (510 words)

	aperiodic tiling
		A tiling made from the same basic elements or tiles that can cover an arbitrarily large surface without ever exactly repeating itself.
		For a long time it was thought that whenever tiles could be used to make an aperiodic tiling, those same tiles could also be fitted together in a different way to make a periodic tiling.
		Then, in the 1960s, mathematicians began finding sets of tiles that were uniquely aperiodic.
	www.daviddarling.info /encyclopedia/A/aperiodic_tiling.html (150 words)

	Reptiling a torus (Site not responding. Last check: 2007-10-30)
		see a 1-tile set that does aperiodically (in a sequential way of thinking of this) tile a torus, but not the plane.
		Furthermore, can we always produce an aperiodic sequence of tiles such that each element of the tile set on the : cylinders can be 'wrapped around' to form a torus of arbitrarily long length (and constant 'hose' diameter) that actually always : tiles the torus?
		It would be nice to : see a 1-tile set that does aperiodically (in a sequential way of thinking of this) tile a torus, but not the plane.
	www.mathpuzzle.com /wwwboard/messages/27.html (551 words)

	Aperiodic Digraph Fractiles (Site not responding. Last check: 2007-10-30)
		In the 1970's,Roger Penrose discovered several types of aperiodic tilings of the plane.
		(A tiling is called aperiodic, if no translation maps every tile to another tile.) It turns out that digraph self-similarity provides a fresh look at his tiles.
		You may download a copy of a paper I have written on this topic in PDF format and the notebook which generated the figures for the paper.
	www.unca.edu /~mcmcclur/mathematicaGraphics/DigraphFractiles/index.html (86 words)

	Ercim Research Report 0197-R046 (Site not responding. Last check: 2007-10-30)
		Rather, we precompute a small set of texture maps which we then map aperiodically onto the surface.
		The algorithm borrows from recent mathematical results in the area of aperiodic tilings of the plane.
		To demonstrate the feasibility of the method we apply it to the rendering of water surfaces and caustics.
	www.ercim.org /publication/technical_reports/046-abstract.html (113 words)

	IUCr COMMISSION ON APERIODIC CRYSTALS (Site not responding. Last check: 2007-10-30)
		In the following, by "crystal" we mean any solid having an essentially discrete diffraction diagram, and by "aperiodic crystal" we mean any crystal in which three dimensional lattice periodicity can be considered to be absent.
		As an extension, the latter term will also include those crystals in which three dimensional periodicity is too weak to describe significant correlations in the atomic configuration, but which can be properly described by crystallographic methods developed for actual aperiodic crystals.
		5) To promote cooperation between crystallographers working on aperiodic crystals and mathematicians working in the field of high-dimensional symmetry groups and/or aperiodic systems, and to stimulate the development ot mathematical crystallography.
	math.smith.edu /Local/aperiodic/terms.html (343 words)

	Research News: Of Friction and "The Da Vinci Code"
		In a paper published in the August 26 issue of the journal Science, a research collaboration led by Miquel Salmeron, a physicist with Berkeley Lab's Materials Sciences Division, reports on the first study to measure the frictional effects of periodicity in a crystalline lattice.
		Geometric periodicity was confirmed via rows of atoms that formed a Fibonacci sequence, a numerical pattern often observed in quasicrystals — and which was one of the clues to solving the Da Vinci code in the novel by Dan Brown.
		By cutting a single Al‑Ni-Co quasicrystal parallel to its ten-fold axis, the researchers were able to produce a two-dimensional surface with one periodic axis and one aperiodic axis, separated by 90 degrees.
	www.lbl.gov /Science-Articles/Archive/MSD-friction-code.html (984 words)

	Summer School in Aperiodic Order (Site not responding. Last check: 2007-10-30)
		Mathematically speaking the term `aperiodic order' is used to describe various geometric objects (such as certain tilings or tessellations of Euclidean space) which are non-periodic and yet display a remarkable degree of regularity.
		The objects of the mathematics of aperiodic order have become the models for these `quasi-crystals' and reciprocally their physics has continued to stimulate directions for research.
		Although less than fifty years old, the mathematics of aperiodic order has grown rapidly and is now an area of considerable activity.
	www.pims.math.ca /ssao (370 words)

	EliteCarAudio.com : Your one stop resource for mobile audio and electronics on the net.
		An Aperiodic enclosure is one in which the woofer breathes thru a resistive membrane to control it's cone characteristics.
		In laymen's terms, it makes a woofer in a tiny enclosure act as if it were in a large, sealed enclosure.
		Physical characteristics---AP’s are the smallest types of enclosures you can make (short of free-air), and in vehicles where space is at a premium they work wonders at getting great bass response into the car.
	www.elitecaraudio.com /article.php?sid=18 (519 words)

	QUANTUM-D: Nonlocality and aperiodic tilings (Site not responding. Last check: 2007-10-30)
		Date: Fri, 14 Mar 1997 00:58:28 -0800 (PST) From: Mitchell Porter <mitch@thehub.com.au> To: quantum-d@teleport.com Subject: Nonlocality and aperiodic tilings In _The Emperor's New Mind_ Roger Penrose discusses aperiodic tilings of the plane - coverings of the plane by numerous copies of a few basic shapes, Escher-fashion, which do not repeat.
		He then describes some materials called quasicrystals, which seem to exhibit properties (10-fold rotational symmetry) resembling some of the aperiodic tilling patterns, and speculates that some nonlocal quantum process is behind the assembly of quasicrystals.
		Think of the spin networks which are the subject of much research in quantum gravity at the moment.
	www.nonlocal.com /quantum-d/v2/mporter_03-14-97.html (271 words)

	Synthetic Utilization Bounds for Aperiodic Systems (Site not responding. Last check: 2007-10-30)
		Among recent advances in real-time schedulability analysis, derivation of the first synthetic utilization-based bounds for aperiodic systems have been path-breaking.
		The theory is promising and there has been much interest in analyzing the advantages and limitations of synthetic utilization-based aperiodic bounds.
		To provide an understanding of the usefulness of synthetic utilization bounds for aperiodic systems, a simulation-based study of their applicability and performance will be presented.
	www.cs.virginia.edu /colloquia/event313.html (91 words)

	Aperiodic Tiling @ AlienArtifacts.com (Alien Artifacts) (Site not responding. Last check: 2007-10-30)
		This page contains quite a lot of relevant information about Aperiodic tiling.
		Residents of planet Earth recounted seeing 105 UFOs to the National UFO Reporting Center in only the first 16 days of July, and many were in California.
		More Aperiodic Tiling Page Titles on this Site
	www.alienartifacts.com /encyclopedia/Aperiodic_tiling (102 words)

	C:\PROGRA~1\TEXTBR~1\TEXTDO~1\TITANI~1.HTM
		-tracks begin to overlap, producing aperiodic domains; in the most damaged titanite examined, there were approximately equal amounts of coexisting crystalline and aperiodic material.
		All information is consistent with the Ewing model for metamict materials, an aperiodic random network structure; HRTEM images show patterns of random contrast consistent with the random network model, with no evidence to support any microcrystalline model of the metamict state.
		We suggest that the original structure is recovered when the ratio of surface area to volume for the damaged material is high, and the interface can exert a strong memory effect on the amorphous material; when large equant aperiodic domains form, they are annealed to a more defect-free and relatively stable aperiodic network structure.
	minerals.gps.caltech.edu /manuscripts/1991/titanite/index.htm (843 words)

Try your search on: Qwika (all wikis)