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61.
Greedy versus social: resource-competing oscillator network as a model of amoeba-based neurocomputer
A single-celled amoeboid organism, the true slime mold Physarum polycephalum, exhibits rich spatiotemporal oscillatory behavior and sophisticated computational capabilities. The authors previously created
a biocomputer that incorporates the organism as a computing substrate to search for solutions to combinatorial optimization
problems. With the assistance of optical feedback to implement a recurrent neural network model, the organism changes its
shape by alternately growing and withdrawing its photosensitive branches so that its body area can be maximized and the risk
of being illuminated can be minimized. In this way, the organism succeeded in finding the optimal solution to the four-city
traveling salesman problem with a high probability. However, it remains unclear how the organism collects, stores, and compares
information on light stimuli using the oscillatory dynamics. To study these points, we formulate an ordinary differential
equation model of the amoeba-based neurocomputer, considering the organism as a network of oscillators that compete for a
fixed amount of intracellular resource. The model, called the “Resource-Competing Oscillator Network (RCON) model,” reproduces
well the organism’s experimentally observed behavior, as it generates a number of spatiotemporal oscillation modes by keeping
the total sum of the resource constant. Designing the feedback rule properly, the RCON model comes to face a problem of optimizing
the allocation of the resource to its nodes. In the problem-solving process, “greedy” nodes having the highest competitiveness
are supposed to take more resource out of other nodes. However, the resource allocation pattern attained by the greedy nodes
cannot always achieve a “socially optimal” state in terms of the public cost. We prepare four test problems including a tricky
one in which the greedy pattern becomes “socially unfavorable” and investigate how the RCON model copes with these problems.
Comparing problem-solving performances of the oscillation modes, we show that there exist some modes often attain socially
favorable patterns without being trapped in the greedy one. 相似文献
62.
63.
Contaminant intrusion in a water distribution network is a complex but a commonly observed phenomenon, which depends on three elements – a pathway, a driving force and a contamination source. However, the data on these elements are generally incomplete, non-specific and uncertain. In an earlier work, Sadiq, Kleiner, and Rajani (2006) have successfully applied traditional Dempster–Shafer theory (DST) to estimate the “risk” of contaminant intrusion in a water distribution network based on limited uncertain information. However, the method used for generating basic probability assignment (BPA) was not very flexible, and did not handle and process uncertain information effectively. In this paper, a more pragmatic method is proposed that utilizes “soft” computing flexibility to generate BPAs from uncertain information. This paper compares these two methods through numerical examples, and demonstrates the efficiency and effectiveness of modified method. 相似文献
64.
Yue WangAuthor Vitae Yasushi HasebeAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):722-729
Horseradish peroxidase (HRP) was chemically modified using cyanuric chloride (CC) as a linking agent onto a carbon felt (CF), which is a microelectrode ensemble of micro carbon fiber (>7 μm, diameter) with a random three-dimensional structure. The resulting HRP-modified CF (HRP-ccCF) exhibited well-defined redox waves based on the HRP heme FeIII/FeII redox couple at −0.23 V vs. Ag/AgCl (at pH 7.0), while the HRP-adsorbed CF (HRP-CF) showed no apparent redox couple in the same potential range, indicating that the chemical modification of HRP via CC facilitated the direct electron transfer (DET) between HRP and CF. The apparent heterogeneous electron transfer rate constant ks was estimated to be 35 s−1. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the interfacial properties (i.e., structure, morphology of enzyme-layer) of covalently modified HRP (HRP-ccCF) and physically adsorbed HRP (HRP-CF) are different, resulting in the difference in the electron transfer properties. The HRP-ccCF was successfully used as a working electrode unit in bioelectrocatalytic flow-through detector for highly sensitive amperometric determination of H2O2. Under the optimized conditions (i.e., applied potential, 0 V vs. Ag/AgCl; carrier flow rate, 3.25 ml/min; and carrier pH 7.0), the cathodic peak current of H2O2 linearly increased up to 3 μM (sensitivity, 1.94 μA/μM; the detection limit, 0.08 μM [S/N = 3]) with sample through-put of ca. 90 samples/h. 相似文献
65.
66.
Amoeba-based Chaotic Neurocomputing: Combinatorial Optimization by Coupled Biological Oscillators 总被引:1,自引:0,他引:1
Masashi Aono Yoshito Hirata Masahiko Hara Kazuyuki Aihara 《New Generation Computing》2009,27(2):129-157
We demonstrate a neurocomputing system incorporating an amoeboid unicellular organism, the true slime mold Physarum, known to exhibit rich spatiotemporal oscillatory behavior and sophisticated computational capabilities. Introducing optical
feedback applied according to a recurrent neural network model, we induce that the amoeba’s photosensitive branches grow or
degenerate in a network-patterned chamber in search of an optimal solution to the traveling salesman problem (TSP), where
the solution corresponds to the amoeba’s stably relaxed configuration (shape), in which its body area is maximized while the
risk of being illuminated is minimized.Our system is capable of reaching the optimal solution of the four-city TSP with a
high probability. Moreover, our system can find more than one solution, because the amoeba can coordinate its branches’ oscillatory
movements to perform transitional behavior among multiple stable configurations by spontaneously switching between the stabilizing
and destabilizing modes. We show that the optimization capability is attributable to the amoeba’s fluctuating oscillatory
movements. Applying several surrogate data analyses, we present results suggesting that the amoeba can be characterized as
a set of coupled chaotic oscillators.
相似文献
Kazuyuki AiharaEmail: |
67.
This paper presents an algebraic approach to polynomial spectral factorization, an important mathematical tool in signal processing and control. The approach exploits an intriguing relationship between the theory of Gröbner bases and polynomial spectral factorization which can be observed through the sum of roots, and allows us to perform polynomial spectral factorization in the presence of real parameters. It is discussed that parametric polynomial spectral factorization enables us to express quantities such as the optimal cost in terms of parameters and the sum of roots. Furthermore an optimization method over parameters is suggested that makes use of the results from parametric polynomial spectral factorization and also employs two quantifier elimination techniques. This proposed approach is demonstrated in a numerical example of a particular control problem. 相似文献
68.
Recently, various techniques of shape reconstruction using cast shadows have been proposed. These techniques have the advantage
that they can be applied to various scenes, including outdoor scenes, without using special devices. Previously proposed techniques
usually require calibration of camera parameters and light source positions, and such calibration processes limit the range
of application of these techniques. In this paper, we propose a method to reconstruct 3D scenes even when the camera parameters
or light source positions are unknown. The technique first recovers the shape with 4-DOF indeterminacy using coplanarities
obtained by cast shadows of straight edges or visible planes in a scene, and then upgrades the shape using metric constraints
obtained from the geometrical constraints in the scene. In order to circumvent the need for calibrations and special devices,
we propose both linear and nonlinear methods in this paper. Experiments using simulated and real images verified the effectiveness
of this technique. 相似文献
69.
The model selection paradigm is one of the focused themes within decision science. This paper addresses the consistent solution of model selection issue on the basis of the fuzzy axiomatic design (FAD) methodology. Moreover, the developed FAD–based model selection interface (FAD–MSI) is performed over the critical ship management processes in order to assign suitable (multiple criteria decision-making) MCDM techniques even if commonly utilized hybrid approaches. The outcomes of this study encourage the maritime practitioners for the further researches towards analytical modelling of ship management processes. 相似文献
70.
Ming-Chi Lee 《Expert systems with applications》2009,36(8):10896-10904
In this paper, we developed a prediction model based on support vector machine (SVM) with a hybrid feature selection method to predict the trend of stock markets. This proposed hybrid feature selection method, named F-score and Supported Sequential Forward Search (F_SSFS), combines the advantages of filter methods and wrapper methods to select the optimal feature subset from original feature set. To evaluate the prediction accuracy of this SVM-based model combined with F_SSFS, we compare its performance with back-propagation neural network (BPNN) along with three commonly used feature selection methods including Information gain, Symmetrical uncertainty, and Correlation-based feature selection via paired t-test. The grid-search technique using 5-fold cross-validation is used to find out the best parameter value of kernel function of SVM. In this study, we show that SVM outperforms BPN to the problem of stock trend prediction. In addition, our experimental results show that the proposed SVM-based model combined with F_SSFS has the highest level of accuracies and generalization performance in comparison with the other three feature selection methods. With these results, we claim that SVM combined with F_SSFS can serve as a promising addition to the existing stock trend prediction methods. 相似文献