These are my recent Pinboard.in links:
Welcome to the Group Pattern Language Project | Group Works
“This deck of 91 full-colour cards names what skilled facilitators and other participants do to make things work. The content is more specific than values and less specific than tips and techniques, cutting across existing methodologies with a designer’s eye to capture the patterns that repeat. The deck can be used to plan sesssions, reflect on and debrief them, provide guidance, and share responsibility for making the process go well. It has the potential to provide a common reference point for practitioners, and serve as a framework and learning tool for those studying the field. ”
via:bkerr collaboration design-patterns tools social-dynamics[1202.0001] Vector-based model of elastic bonds for DEM simulation of solids
“A new model for computer simulation of solids, composed of bonded particles, is proposed. Vectors rigidly connected with particles are used for description of deformation of a single bond. The expression for potential energy of the bond and corresponding expressions for forces and moments are proposed. Formulas, connecting parameters of the model with longitudinal, shear, bending and torsional stiffnesses of the bond, are derived. It is shown that the model allows to describe any values of the bond stiffnesses exactly. Two different calibration procedures depending on bond length/thickness ratio are proposed. It is shown that parameters of model can be chosen so that under small deformations the bond is equivalent to either Bernoulli-Euler or Timoshenko rod or short cylinder connecting particles. Simple expressions, connecting parameters of V-model with geometrical and mechanical characteristics of the bond, are derived. Computer simulation of dynamical buckling of the straight discrete rod and discrete half-spherical shell is carried out.”
modeling mechanical-systems materials-science computational-methods algorithms nudge-targets- “Inspired by birds flying through cluttered environments such as dense forests, this paper studies the theoretical foundations of a novel motion planning problem: high-speed navigation through a randomly-generated obstacle field when only the statistics of the obstacle generating process are known a priori. Resembling a planar forest environment, the obstacle generating process is assumed to determine the locations and sizes of disk-shaped obstacles. When this process is ergodic, and under mild technical conditions on the dynamics of the bird, it is shown that the existence of an infinite collision-free trajectory through the forest exhibits a phase transition. On one hand, if the bird flies faster than a certain critical speed, then, with probability one, there is no infinite collision-free trajectory, i.e., the bird will eventually collide with some tree, almost surely, regardless of the planning algorithm governing the bird’s motion. On the other hand, if the bird flies slower than this critical speed, then there exists at least one infinite collision-free trajectory, almost surely. Lower and upper bounds on the critical speed are derived for the special case of a homogeneous Poisson forest considering a simple model for the bird’s dynamics. For the same case, an equivalent percolation model is provided. Using this model, the phase diagram is approximated in Monte-Carlo simulations. This paper also establishes novel connections between robot motion planning and statistical physics through ergodic theory and percolation theory, which may be of independent interest.”
robotics planning algorithms nudge-targets [1202.0077] An Interacting Particle Model for Clustering Euclidean Datasets
“In this paper we propose a method based on interacting particle physics, devised for clustering Euclidean datasets without initial constraints or conditions. We model any dataset as an interacting particle system, whose elements correspond to particles that interact through a simplified version of Lennard-Jones potentials. In so doing, mutual attractive interactions allow to identify groups of proximal particles. The main outcome of this modeling task is an adjacency matrix, taken as input by a community detection algorithm aimed to identify different partitions. The underlying conjecture is that, using a multiresolution analysis, the adopted model allows to find the right number of clusters for any given dataset. Experimental results, performed in comparison with a classical clustering algorithm, confirm this assumption.”
clustering data-analysis algorithms nudge-targets distributed-processing[1201.6583] Empowerment for Continuous Agent-Environment Systems
“This paper develops generalizations of empowerment to continuous states. Empowerment is a recently introduced information-theoretic quantity motivated by hypotheses about the efficiency of the sensorimotor loop in biological organisms, but also from considerations stemming from curiosity-driven learning. Empowemerment measures, for agent-environment systems with stochastic transitions, how much influence an agent has on its environment, but only that influence that can be sensed by the agent sensors. It is an information-theoretic generalization of joint controllability (influence on environment) and observability (measurement by sensors) of the environment by the agent, both controllability and observability being usually defined in control theory as the dimensionality of the control/observation spaces.…”
agent-based emergent-design robotics engineering-design machine-learning empowerment nudge[1201.6655] Learning Performance of Prediction Markets with Kelly Bettors
“In evaluating prediction markets (and other crowd-prediction mechanisms), investigators have repeatedly observed a so-called “wisdom of crowds” effect, which roughly says that the average of participants performs much better than the average participant. The market price—an average or at least aggregate of traders’ beliefs—offers a better estimate than most any individual trader’s opinion. In this paper, we ask a stronger question: how does the market price compare to the best trader’s belief, not just the average trader. We measure the market’s worst-case log regret, a notion common in machine learning theory. To arrive at a meaningful answer, we need to assume something about how traders behave. We suppose that every trader optimizes according to the Kelly criteria, a strategy that provably maximizes the compound growth of wealth over an (infinite) sequence of market interactions. We show several consequences.…”
prediction performance-measure agent-based simulation nudge-targets wisdom-of-crowds- ‘This is why “curate” is still a word to conjure by in our culture. It still promises transformative power.’
museology pragmatics naming engineering-of-philosophy [1201.5780] Full and Half Gilbert Tessellations with Rectangular Cells
“We investigate the ray-length distributions for two different rectangular versions of Gilbert’s tessellation. In the full rectangular version, lines extend either horizontally (with east– and west-growing rays) or vertically (north– and south-growing rays) from seed points which form a Poisson point process, each ray stopping when another ray is met. In the half rectangular version, east and south growing rays do not interact with west and north rays. For the half rectangular tessellation we compute analytically, via recursion, a series expansion for the ray-length distribution, whilst for the full rectangular version we develop an accurate simulation technique, based in part on the stopping-set theory of Zuyev, to accomplish the same. We demonstrate the remarkable fact that plots of the two distributions appear to be identical when the intensity of seeds in the half model is twice that in the full model. Our paper explores this coincidence mindful of the fact that, for one model, our results are from a simulation (with inherent sampling error).…”
geometry tiling algorithms generative-art simulation emergence interesting-problem