arXiv subjects

P. Fraundorf

Publications and source records attributed to P. Fraundorf.

At least 19 recordsLinked to original sources

arXiv2019

Log Complex Color for Visual Pattern Recognition of Total Sound

While traditional audio visualization methods depict amplitude intensities vs. time, such as in a time-frequency spectrogram, and while some may use complex phase information to augment the amplitude representation, such as in a reassigned spectrogram, the phase data are not generally represented in their own right. By plotting amplitude intensity as brightness/saturation and phase-cycles as hue-variations, our complex spectrogram method displays both amplitude and phase information simultaneously, making such images canonical visual representations of the source wave. As a result, the original sound may be precisely reconstructed (down to the original phases) from an image, simply by reversing our process. This allows humans to apply our highly developed visual pattern recognition skills to complete audio data in new way.

cs.SD↗

arXiv2015

A graphite-prism definition for Avogadro's "integer"

The new International System of Units may let us select an integer value for Avogadro's number. Some might prefer an integer that's divisible by 12, so that an integer number of $^{12}C$ atoms may be associated (to first order) with a gram's mass. For educational and practical reasons it may also help to choose a {\em physically-meaningful} definition within measurement error of the current numeric value. Cubes of diamond face-centered-cubic Si and (much rarer) face-centered-cubic C have been proposed, but these structures do not have naturally-occurring facets (or numbers of atoms generally divisible by 12). We show here that graphite prisms formed by stacking $m$ hexagonal graphene sheets, with $m \equiv 51,150,060$ carbon-12 atoms on each side, are a natural solution that may facilitate generation of precise molar standards as well.

physics.gen-ph↗

arXiv2014

Microwave Bragg-scattering zone-axis-pattern analysis

Louis deBroglie's connection between momentum and spatial-frequency vectors is perhaps most viscerally-experienced via the real-time access that electron-diffraction provides to transverse slices of a nano-crystal's reciprocal-lattice. The classic introductory (and/or advanced) physics lab-experiment on microwave Bragg-scattering can with a bit of re-arrangement also give students access to "zone-axis-pattern" slices through the 3D spatial-frequency (i.e. reciprocal) lattice of a ball-bearing crystal, which may likewise contain only a few unit-cells. In this paper we show how data from the standard experimental set-up can be used to generate zone-axis-patterns oriented down the crystal rotation-axis. This may be used to give students direct experience with interpretation of lattice-fringe image power-spectra, and with nano-crystal electron-diffraction patterns, as well as with crystal shape-transforms that we use here to explain previously mis-identified peaks in the microwave data.

physics.ed-ph↗

arXiv2014

A traveler-centered intro to kinematics

Treating time as a local variable permits robust approaches to kinematics that forego questions of extended-simultaneity, which because of their abstract nature might not be addressed explicitly until a first relativity course and even then without considering the dependence of clock-rates on position in a gravitational field. For example we here use synchrony-free ``traveler kinematic" relations to construct a brief story for beginning students about: (a) time as a local quantity like position that depends on ``which clock", (b) coordinate-acceleration as an approximation to the acceleration felt by a moving traveler, and (c) the geometric origin (hence mass-independence) of gravitational acceleration. The goal is to explicitly rule out global-time for all from the start, so that it can be returned as a local approximation, while tantalizing students interested in the subject with more widely-applicable equations in range of their math background.

physics.pop-ph↗

arXiv2013

Layer-multiplicity as a community order-parameter

A small number of (perhaps only 6) broken-symmetries, marked by the edges of a hierarchical series of physical {\em subsystem-types}, underlie the delicate correlation-based complexity of life on our planet's surface. Order-parameters associated with these broken symmetries might in the future help us broaden our definitions of community health. For instance we show that a model of metazoan attention-focus, on correlation-layers that look in/out from the 3 boundaries of skin, family & culture, predicts that behaviorally-diverse communities require a characteristic task layer-multiplicity {\em per individual} of only about $4 \frac14$ of the six correlation layers that comprise that community. The model may facilitate explorations of task-layer diversity, go beyond GDP & body count in quantifying the impact of policy-changes & disasters, and help manage electronic idea-streams in ways that strengthen community networks. Empirical methods for acquiring task-layer multiplicity data are in their infancy, although experience-sampling via cell-phone button-clicks might be one place to start.

physics.gen-ph↗

arXiv2013

Metric-first & entropy-first surprises

Established idea-sets don't update seamlessly. The tension between new and old views of nature is e.g. documented in Galileo's dialogs and now present in many fields. However the science of Bayesian model-selection has made recent strides in both life & physical sciences, in effect suggesting that we look to models which are quantitatively {\em surprised least} by present-day observations. We illustrate the relevance of this to physics-education with a qualitative look at two paradigm-shifts, namely from {\bf Lorentz-transform to metric-equation} descriptions of motion in space-time, and from {\bf classical to statistical thermodynamics} with help from Boltzmann's choice-multiplicity & Shannon's uncertainty. Connections of the latter to {\bf correlation measures} behind available-work, evolving complexity, and model-selection relevant to physics undergrads are also explored. New strategies are exemplified with Appendices {\em for teachers} on: anyspeed traffic-laws & 3-vector velocity-addition, the energy-momentum half-plane lost to finite lightspeed, the modern distinction between proper & geometric accelerations, metric-first kinematics with acceleration & differential-aging, quantifying risk with a handful of coins, effective number of choices, available work in bits, reversible-thermalization of life's power-stream, and choice-multiplicity measures of layered complex-system health.

physics.gen-ph↗

arXiv2012

Zero-loss/deflection map analysis

Experimental plots of the fraction of detected electrons removed from the zero-loss peak, versus the fraction of incident electrons scattered outside of the objective aperture, can serve as a robust fingerprint of object-contrast in an energy filtered transmission electron microscope (EFTEM). Examples of this, along with the first in a series of models for interpreting the resulting patterns, were presented at the August 2010 meeting of the Microscope Society of America meeting in Portland, Oregon, and published in {\em Microscopy and MicroAnalysis} {\bf 16}, Supplement 2, pages 1534-1535 by Cambridge University Press.

physics.gen-ph↗

arXiv2011

The thermal roots of correlation-based complexity

Bayesian maxent lets one integrate thermal physics and information theory points of view in the quantitative study of complex systems. Since net surprisal (a free energy analog for measuring "departures from expected") allows one to place second law constraints on mutual information (a multi-moment measure of correlations), it makes a quantitative case for the role of reversible thermalization in the natural history of invention, and suggests multiscale strategies to monitor standing crop as well. It prompts one to track evolved complexity starting from live astrophysically-observed processes, rather than only from evidence of past events. Various gradients and boundaries that play a role in availability flow, ranging from the edge of a wave-packet to the boundary between idea-pools, allow one to frame wide-ranging correlations (including that between a phenomenon and its explanation) as delocalized {\em physical} structures.

physics.gen-ph↗

arXiv2007

A simplex model for layered niche networks

The standing crop of correlations in metazoan communities may be assessed by an inventory of niche structures focused inward and outward from the physical boundaries of skin (self), gene-pool (family), and meme-pool (culture). We consider tracking the progression from three and four correlation layers in many animal communities, to five of six layers for the shared adaptation of most humans, with an attention-slice model that maps the niche-layer focus of individuals onto the 6-variable space of a 5-simplex. The measure puts questions about the effect, on culture and species, of policy and natural events into a common context, and may help explore the impact of electronically-mediated codes on community health.

physics.gen-ph↗

arXiv2006

Friendly units for coldness

Measures of temperature that center around human experience get lots of use. Of course thermal physics insights of the last century have shown that reciprocal temperature (1/kT) has applications that temperature addresses less well. In addition to taking on negative absolute values under population inversion (e.g. of magnetic spins), bits and bytes turn 1/kT into an informatic measure of the thermal ambient for developing correlations within any complex system. We show here that, in the human-friendly units of bytes and food Calories, water freezes when 1/kT ~200 ZB/Cal or kT ~5 Cal/YB. Casting familiar benchmarks into these terms shows that habitable human space requires coldness values (part of the time, at least) between 0 and 40 ZB/Cal with respect body temperature ~100 degrees F, a range in kT of ~1 Cal/YB. Insight into these physical quantities underlying thermal equilibration may prove useful for budding scientists, as well as the general public, in years ahead.

physics.pop-ph↗

arXiv2006

Unlayered graphenes in red-giant starsmoke

Electron diffraction, imaging, and energy loss provide evidence for unlayered graphene sheets in the core of certain interstellar graphite onions (from the meteorite Murchison) whose isotopes indicate formation in the atmosphere of late-stage asymptotic giant branch stars (like those which nucleo-synthesized much of the earth's carbon). The data are compared to structural models loosely associated with atom-by-atom, molecule-by-molecule, and dendritic-droplet solidification processes. In this context the observed density, diffraction peak-shapes, and edge-on sheet patterns, along with theoretical limits on time for growth in the presence of outgoing radiation pressure, suggest nucleation of hexagonal sheets from pentagons, perhaps from a supercooled melt. These results warrant a closer examination of specimen structure, the energetics of unlayered graphene nucleation, and processes such as jets in late star atmospheres.

cond-mat.mtrl-sci↗

arXiv2006

Lattice fringe signatures of epitaxy on nanotubes

Carbon nanotubes are of potential interest as heterogeneous catalysis supports, in part because they offer a high surface area hexagonal array of carbon atoms for columnar or epitaxial attachment. Fringe visibility modeling of electron microscope lattice images allows one to investigate the relationship between individual nanoparticles and such nanotube supports. We show specifically how (111) columnar or epitaxial growth of FCC metal lattices, on carbon nanotubes viewed side-on, results in well-defined patterns of (111)-fringe orientations with respect to the tube axis. In the epitaxial case, the observations also provide information on chirality of the nanotube's outermost graphene sheet.

cond-mat.mtrl-sci↗

arXiv2006

Elements, topology, and T-shirts

Consider the network of elements connected by adjacency in atomic number and periodic table column. If all elements except H-He are connected by identical springs and constrained to a z-spiral in 2D, a map sans spring-crossing results for various values of rest length in units of the H-He distance. If the z-spiral is removed, and the network allowed to relax in 3D, the resulting surface with three holes has the topology of a T-shirt or open-handle teapot. Mapping this to a shirt's front-back pattern yields a 2D table of elemental inter-connects in tabular (nearly rectilinear) form. Sample applications: The flat spiral (like other spiral patterns) might serve as basis for an educational board game, while the T-shirt table might serve as a starting point for ``topologically informed'' classroom periodic-table design projects with wearable awards.

physics.ed-ph↗

arXiv2005

Modernizing Newton, to work at any speed

Modification of three ideas underlying Newton's original world view, with only minor changes in context, might offer two advantages to introductory physics students. First, the students will experience less cognitive dissonance when they encounter relativistic effects. Secondly, the map-based Newtonian tools that they spend so much time learning about can be extended to high speeds, non-inertial frames, and even (locally, of course) to curved-spacetime.

physics.ed-ph↗

arXiv2005

Making sense of nanocrystal lattice fringes

The orientation-dependence of thin-crystal lattice fringes can be gracefully quantified using fringe-visibility maps, a direct-space analog of Kikuchi maps. As in navigation of reciprocal space with the aid of Kikuchi lines, fringe-visibility maps facilitate acquisition of 3D crystallographic information in lattice images. In particular, these maps can help researchers to determine the 3D lattice parameters of individual nano-crystals, to ``fringe fingerprint'' collections of randomly-oriented particles, and to measure local specimen-thickness with only modest tilt. Since the number of fringes in an image increases with maximum spatial-frequency squared, these strategies (with help from more precise goniometers) will be more useful as aberration-correction moves resolutions into the subangstrom range.

cond-mat.mtrl-sci↗

arXiv2004

Heterogeneity, and the secret of the sea

This paper explores tools for modeling and measuring the compositional heterogeneity of a rock, or other solid specimen. Intuitive ``variation per decade'' plots, simple expressions for containment probability, generalization for familiar error-in-the-mean expressions, and a useful dimensionless sample bias coefficient all emerge from the analysis. These calculations have also inspired subsequent work on log-log roughness spectroscopy (with applications to scanning probe microscope data), and on angular correlation mapping of lattice fringe images (with applications in high resolution transmission electron microscopy). It was originally published as Appendix E of a dissertation on ``Microcharacterization of interplanetary dust collected in the earth's stratosphere''.

cond-mat.mtrl-sci↗

arXiv2004

Digital darkfield decompositions

Lattice imaging facilitates digital implementation of optical darkfield strategies that have for decades played a key role in the conventional electron microscopy of materials. Applications to the microscopy of periodic structures are described in the context of recent developments in the mathematical harmonic analysis community, with hopes of inspiring further development along these lines. Applications here, which push present day limits using sharp-edged Fourier windows alone, include the location of weak periodicities in images by virtue of their spatial correlations, and the quantitative mapping of projected strain in a variety of nanostructures.

cond-mat.mtrl-sci↗

arXiv2003

Information physics: From energy to codes

We illustrate in terms familiar to modern day science students that: (i) an uncertainty slope mechanism underlies the usefulness of temperature via its reciprocal, which is incidentally around 42 [nats/eV] at the freezing point of water; (ii) energy over kT and differential heat capacity are ``multiplicity exponents'', i.e. the bits of state information lost to the environment outside a system per 2-fold increase in energy and temperature respectively; (iii) even awaiting description of ``the dice'', gambling theory gives form to the laws of thermodynamics, availability minimization, and net surprisals for measuring finite distances from equilibrium, information content differences, and complexity; (iv) heat and information engine properties underlie the biological distinction between autotrophs and heterotrophs, and life's ongoing symbioses between steady-state excitations and replicable codes; and (v) mutual information resources (i.e. correlations between structures e.g. a phenomenon and its explanation, or an organism and its niche) within and across six boundary types (ranging from the edges of molecules to the gap between cultures) are delocalized physical structures whose development is a big part of the natural history of invention. These tools might offer a physical framework to students of the code-based sciences when considering such disparate (and sometimes competing) issues as conservation of available work and the nurturing of genetic or memetic diversity.

physics.ed-ph↗