CCSR Technical Reports, 1995-99

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Technical Reports: 1999

Technical Reports: 1998

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Technical Reports: 1996

Technical Reports: 1995

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CCSR Technical Reports,
with Abstracts: 1995-99

Technical Reports, with Abstracts: 1999

M. Sperl, A Chang, N. Weber, A. Hübler, Hebbian Learning in the Agglomeration of Conducting Particles , Technical Report CCSR-99-1

Abstact: The Hebbian learning rule is a fundamental concept in the learning of a neuronal net, where a frequently used connection of two neutrons is continually reinforced. We study the properties of self- assembling connections of conducting particles in a dielectic liquid, and find that the strength of the connection between the different electrodes represents a memory for the history of the system. Optimal parameters and sequences of simulation for effective training are determined. We discuss a future application of our results for the implementation of a nonvolatile neuronal network based on self-assembling nanowires on a semiconductor surface. Reprint

Technical Reports, with Abstracts: 1998

A. Hübler, C. Martinez, A Complex System Perspective to Computer-Assisted Learning , Technical Report CCSR-98-1

Abtract: Web technology has made it possible for the Internet to penetrate a large proportion of American society. The educational sector has lagged behind the progress curve, however. This lag in the application of technology in education is due to not only financial reasons but also because education is more than information delivery and simulation. To teach a student via the Web, at least two components are required: a human computer interface that resonates with the student and artificial intelligence that understands specific areas of knowledge and applies appropriate responses. It is in this content that we study an asynchronous learning environment, Cyberprof^TM, where we apply several fundamental complex systems paradigms to human computer interaction: nonlinear resonances applied in a Digital Mirror, dynamical reconstruction applied in a Field-Specific Tutor and control of chaos applied in a Five Senses Human Computer Interface. To measure the effectiveness of the new learning environment we propose to use a Differential Concept Analysis (DCA). In DCA we monitor student's actions step by step, determine which concepts the students are using, in which sequence the concepts are used, and if the students are able to substitute and alter the sequence of the applied concepts. Reprint

Technical Reports, with Abstracts: 1997

M. Dueweke, B. Merté, A. Hübler, Stable Stationary Dendritic Structures with Minimal Resistance , Technical Report CCSR-97-1
Abtract: During the past several years, dendritic growth of the solid phase in an undercooled melt and related transient processes have been investigated experimentally and theoretically. New experiments indicate, that stable agglomerates of metallic balls in an electric field an have fractal geometry and a dendritic structure. It is shown analytically, that the agglomerates approach stable stationary states, where the overall resistance becomes as small as possible, whereas the energy content and the entropy production may have a complicated time dependence. Though in every experiment evolves a different irregular pattern, some macroscopic properties of them are very reproducable. We find a smooth relation between the control parameters of the experiment and those macroscopic quantities. Reprint
R. Weigel, E.A. Jackson, Experimental Implementation of Migrations in Multiple-Attractor Systems , Technical Report CCSR-97-2
Abtract: It was shown by Jackson and Grosu [1995a] that entrainment control of a complex dynamic system could be achieved by using an open-plus-closed-loop (OPCL) control action. Jackson [1995] showed that, for multiple-attractor systems, it is possible to transfer the dynamics of a system between arbitrary attractors, using this control only for a limited period of time ("migration control"). In the case of the Chua system [1986], Jackson and Grosu [1995b] showed that this migration action can be achieved using only a limited pre-recorded signal of one variable of the "target" attractor. Here we study the experimental implementation of this migration action on a Chua circuit with five attractors (fixed points, a limit cycle, and chaotic attractors) [Wu and Pivka, 1994]. It is shown that reliable migrations are possible with a pre-recorded signal of one target variable, provided that the signal is longer than a minimal time, dependent on an adjustable control strength. The minimal time for successful migration is studied for all distinct migration processes. It is also shown that this action is robust to the limited accuracy of the recorded data. Reprint
M. Duez, J. Captain, A. Hübler, Is Quantum Chaos Stable? Does Nature Prefer Order? , Technical Report CCSR-97-3

Abtract: We study the stability of chaos in wave phenomena. To do this, we build, test, and model several nonlinear systems with movable boundaries. We investigate the behavior of wave droplets on a vibrating plate. We also study the motion of a sphere traveling along a string attached to two vibrators. We find that in each of the experiments, chaotic or coupled oscillations tend to be unstable. The water droplets adjust their boundaries until regular motion results. The sphere on the vibrating string will settle at the string wave's regular nodes in the case of random noise. We believe that our results may be applied to other wave phenomena where quantum chaos may be expected to be suppressed. Reprint
E. Kennedy, A. Hübler, Tutoring College Physics Using the World Wide Web , Technical Report CCSR-97-4
Abtract: We studied the methods of tutoring college physics students with and without using computers. We found that using computers is very beneficial to both teachers and students. However, there are certain teaching methods that make the experience more beneficial to the students, enabling them to understand the problem and be more capable of solving similar problems alone. We applied these findings to the CyberProf system on the World Wide Web. Reprint
M. Hinton, A. Fleming, R. Greene, N. Daluga, U. Thakkar, A. Hübler, Authoring Problems by Students for Students: An Advanced Placement Physics High School Project , Technical Report CCSR-97-5

Abtract: Students in advanced placement (AP) physics classes at Champaign Centennial and Urbana High School in Illinois are writing physics problems using CyberProf software on the web. This project involves all students in the classes as authors. As a result, a physics problem-solving community has developed at the two schools.
Consistent with current reform efforts that indicate the importance of active student and teacher involvement in project-centered activities (e.g., Means, 1994), students in two classes are building effective partnerships as they collaborate. In addition, by designing physics problems, students are deepening their own understanding of fundamental concepts. These problems also can be used as tutorials by other students in first-year physics classes. The two classroom teachers have intergrated CyberProf-mediated problem-solving into their curriculum. Emphasis has been placed on students' process of developing and refining conceptual problems for their peers. Assessment has been conducted by peer- and self-evaluation.
In this paper, we provide an overview of CyberProf, motivation for the project, and a summary on the implementation of the project in one classroom. Reprint
D. Raineri, B. Mehrtens, A. Hübler, CyberProf - An Intelligent Human-Computer Interface for Interactive Instruction on the World Wide Web , Technical Report CCSR-97-6
Abtract: Advances in computer technology and the human-computer interface have created a wealth of new opportunities for the development of computer-based instruction and intelligent tutoring systems. Unfortunately, much of the material currently available amounts to little more than "electronic books", in which learning is still accomplished by reading text and viewing two-dimensional images. This paper describes the features of CyberProf - an interactive, World Wide Web-based teaching system developed at the University of Illinois. Using CyberProf, instructors can create on-line lecture notes that include equations, animations, and graphics; write on-line interactive homework problems; communicate with students using CyberProf's Web-based conferencing system; survey students in order to receive feedback on course material; and record student grades in CyberProf's on-line gradebook. Students can review lecture notes 24 hours a day; complete homework problems on the Web and receive immediate intelligent feedback to their answers; use the conferencing system to post questions to their instructor, teaching assistants, and peers; and review their grades in the class at any time. Reprint

Technical Reports, with Abstracts: 1996

P. San Clemente, Study Regarding the Counting of Stable Fixed Points in Biologically Motivated Neural Networks , Technical Report CCSR-96-1

Abtract: This study attempts to count the maximal number of stable fixed points in a general neural network. The networks examined obey a simplified meanfiring dynamics with step function gains. Connection weights are allowed to be completely general, obeying only biologically motivated constraints such as the lack of self-connections and Dale's Law. Exact magnitudes of connection weights and thresholds are avoided in this analysis by exploiting dynamical features and labelling potential fixed points. No completely general results are obtained; however, the maximal number of fixed points is bound from above and below with nontrivial bounds. Reprint
K. Lopez, E. Mosher, B. Mehrtens, D. Raneri, A. Hübler, Adding the Sense of Smell to Cyberworld , Technical Report CCSR-96-2

Abtract: The cyberworld as we currently know it appeals to the senses of sight and sound. It is in our best interest to introduce the sense of smell into this cyberworld. We examine the possibilities of this addition via the use of printers. We analyze the effects of using different chemicals to produce a smell by injecting the chemicals into the ink cartridge of the printer. We find that using chemicals produces the desired smell, however, it only remains a short period of time. Additionally, we analyze the effects of using bacteria, specifically E. coli, in ink cartridges for printing. We find that neither the smell nor the print quality produced the desired results. We relate chemicals used to other different chemicals in order to, in the future, obtain results that produce stronger smell with a longer endurance for maintaining that smell. Reprint

Technical Reports, with Abstracts: 1995

G. Mayer-Kress, Global Brains as Paradigm for a Complex Adaptive World , Technical Report CCSR-95-1

Abtract: Models from natural science often have served as paradigms for many areas including social sciences. We suggested a Global Brain paradigm for modeling a world in which complex adaptive phenomena become one of the most dominant characteristics. Hyper-media documents on the Internet form linked, virtual structures. These can be seen as a global analogy to neuronal cell-assemblies in a biological brain that are considered to provide the basis for cognitive processes like perceptual binding. We performed some simple empirical tests to determine round-trip times to different locations on the Internet as a rough estimator for the current limits for the extension of a Global Brain. Reprint
E.A. Jackson, No Provable Limits to 'Scientific Knowledge' , Technical Report CCSR-95-2 Reprint
E.A. Jackson, An Open-Plus-Closed-Loop (OPCL) Control of Complex Dynamic Systems , Technical Report CCSR-95-3

Abtract: A new method of controlling arbitrary nonlinear dynamic systems, dx/dt = F(x,t)(x∈Rⁿ), is presented. It is proved that there exist solutions, x(t), in the neighborhood of any arbitrary 'goal' dynamics g(t) that are entrained to g(t), through the use of an additive controlling action, K(g,x,t) = H(dg/dt,g) + C(g,t)(g(t)-x) , which is the sum of the open-loop (Hübler) action, H(dg/dt,g), and a suitable linear closed-loop (feedback) action C(g,t). Examples of some newly obtained entrainment capabilities are given for the Duffing and van der Pol systems. For these and the Lorenz, and Rössler systems proofs are given for global basins of entrainment for all goal dynamics that can be exponentially bounded in time. The basin of entrainment is also established for the Chua system, as well as the possibility of a coexisting basin of attraction to another fixed point. Reprint
N. Birbaumer, W. Lutzenberger, H. Rau, G. Mayer-Kress, C. Braun, Perception of Music and Dimensional Complexity of Brain Activity , Technical Report CCSR-95-4

Abtract: The non-linear resonance hypothesis of music perception was tested in an experiment comparing a group of musically sophisticated and a group of less sophisticated subjects. The prediction that weakly chaotic music entrains less complex brain wave (EEG) oscillations at the prefrontal cortex was confirmed by using a correlational dimension algorithm. Strongly chaotic (stochastic) and periodic music both stimulated higher brain wave complexity. More sophisticated subjects who prefer classical music showed higher EEG dimensions while less sophisticated subjects responded with a drop in brain wave complexity to rhythmical weakly chaotic music. Subjects ratings of perceived complexity of the musical pieces followed mathematical (objective) structure of the music and did not reflect the changes in brain wave complexity. The results are interpreted in the context of an associated (Hebbian) network theory of non-linear brain dynamics. Reprint
J. Best, J. Charlton, G. Mayer-Kress, Analysis of Galaxy Morphology and Evolution using the Pointwise Dimension , Technical Report CCSR-95-5

Abtract: In this paper we explore the application of the pointwise dimension (PD) analysis as a large-scale structure descriptor to the RC3 catalog of galaxies (de Vaucouleurs et al. 1991). This technique, which originated in the field of fractal geometry (Mandelbrot, 1982) and found many applications in non-linear dynamics, is particularly illuminating in the study of correlations between morphology and environment. To our knowledge the technicque is being applied for the first time to the study of galaxy morphology and evolution. The PD is the slope of the curve representing the number of galaxies within some radius, determined separately for each galaxy in the catalog. Thus the distributions of PD's can be compared for subsamples based on morphological type or luminosity. The conclusions of this analysis of RC3 are: 1) The PD elucidates the tendency for early-type galaxies to cluster more than late-type galaxies; however, there is considerable overlap between these populations. 2) The PD statistic does not find a significant relationship between luminosity and clustering in RC3, but it could be an effective diagnostic in larger 2D catalogs. 3) The majority of galaxies in RC3 (excluding clusters) are spread out in space much like a random distribution. A population of objects that traces the distribution of galaxies, but avoids clusters, would have only small correlations. It is worthwile to pursue application of the PD to larger catalogs with a wider range of luminosities. Reprint
S. Kümmel, A. Hübler, Self-Assembling Electrical Connections on a Nanoscale , Technical Report CCSR-95-6

Abtract: We study self-constructing and self-repairing electrical connections built by gold atoms on a silicon surface. Our simulation shows the existence of an optimum temperature for the construction process. We also find that for initial particle distributions where the atoms are evenly spaced between the electrodes assembling time is higher and connection stability is lower than for distributions where the atoms are arranged in small clusters. This result is found to be in good agreement with experiments on a macroscopic scale. Extensions and future applications of the model are discussed. Reprint
U. Hansen, A. Hübler, Desalination with Fractal Absorbers in Deep Seawater , Technical Report CCSR-95-7

Abtract: We study the use of fractal absorbers for reverse osmosis desalination in deep sea water. We investigate for what strength of stream which shape of the absorber is ideal. We find that there is no unique fractal shape which gives maximum gain of freshwater independent of the stream effects, but the efficiency varies strongly with the shape of the fractal absorber. We also consider how the amount of energy required for desalination can be lowered by setting up the plant in deep sea water. Reprint
E.A. Jackson, I.Grosu, Toward Experimental Implementation of Migration Controls , Technical Report CCSR-95-8

Abtract: Jackson and Grosu developed a method for controlling complex dynamic systems that employs an open-plus-closed-loop control components (the OPCL method), and proved that it is capable of entraining the dynamics of standard dynamic systems to arbitrary goal dynamics, g(t) ∈ Rⁿ [Jackson and Grosu, 1995]. Rather than use this control for entrainment, one of us (EAJ) has shown [Jackson, 1995] how the OPCL can be easily employed to transfer the dynamics of a multiple-attractor system from one attractor to another ("migration controls" [Jackson, 1990]). For this purpose, a Chua-circuit model with five distinct attractors was used. In the present study we will show how to experimentally implement the OPCL migration control on such a circuit, by using prerecorded signals, which makes it possible to restrict the control action to only one dynamic component. Reprint
P. Jung, Stochastic Resonance and Optimal Design of Threshold Detectors , Technical Report CCSR-95-9

Abtract: We consider the detection of noisy signals with neuron-like threshold crossing detectors in the context of stochastic resonance. On the basis of an exact spectral analysis of the outgoing stochastic spike train, we show for the first time that there are optimal values for the threshold which yield under given environmental conditions optimal performance. Reprint
A. Madureira, P. Jung, P. Hänggi, Dye Laser with Pump and Quantum Noise , Technical Report CCSR-95-10

Abtract: We consider a single mode dye laser with colored pump noise and white quantum fluctuations. A novel analytical approach is applied to study the statistics of the intensity fluctuations for arbitrary correlation times of the pump noise. Full numerical solutions are compared with our novel approximation and previous approximation schemes. Reprint
D. Bensen, A. Scheeline, Reduction of Dimension of a Chemically Realistic Model for the Peroxidase-Oxidase Oscillator , Technical Report CCSR-95-11

Abtract: We develop a low-dimensional model of the peroxidase-oxidase oscillator based on the higher-dimensional Urbanalator-model. The low-dimensional model is consistent with the chemical foundation of the Urbanalator, accurately reproduces its oscillatory behavior, and also bears some similarities to the simpler abstract models. The remaining differences may suggest directions for further model refinements. Reprint
P. Jung, J.G. Kissner, P. Hänggi, Regular and Chaotic Transport in Asymmetric Periodic Potentials: Inertia Ratchets , Technical Report CCSR-95-12

Abtract: Motivated by recent work on stochastic ratchets, we consider the question whether it is possible to have directed motion in periodic potentials in the absence of noise. As a model, we use the underdamped motion of a particle in an asymmetric periodic potential. Characterizing the motion by cumulants of the contracted, time-dependent solution of the Liouville equation, we can distinguish regular from chaotic transport. Chaotic transport is shown to exhibit universal (Gaussian) scaling behavior. This scaling resembles the transport in overdamped stochastic ratchets, including e.g. current reversals. Reprint
A. Hübler, U. Stoffregen, R. Wittmann, T. Nagata, Sharp Diffraction Peaks from Chaotic Structures , Technical Report CCSR-95-13

Abtract: Recently various models for spatially chaotic structures have been proposed. We study the diffraction patterns produced by plane chaotic waves incident on one-dimensional chaotic point scatterers. The spacing between the scatterers and the dynamics of the incident wave are given by a logistic map or standard map. We find a sharp diffraction peak when the incident dynamics is produced by the same map as the structure of the spatial configuration. The diffraction pattern is symmetric about the incident direction only if the map dynamics is invertible. Diffraction patterns with chaotic incident waves have a large signal to noise ratio and are well suited for pattern identification. We discuss possible applications to the scattering of microwaves from aperiodic structures. Reprint

CCSR Technical Reports,with Abstracts: 1995-99

Technical Reports, with Abstracts: 1999

Technical Reports, with Abstracts: 1998

Technical Reports, with Abstracts: 1997

Technical Reports, with Abstracts: 1996

Technical Reports, with Abstracts: 1995

CCSR Technical Reports,
with Abstracts: 1995-99