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This paper discusses an on-line Tasks Assignment and Routing Problem (TARP) for Autonomous Transportation Systems (ATSs) in manufacturing systems. The TARP is a constrained version of the Pickup and Delivery Problem with Time Windows (PDPTW). In our former study, a cooperative algorithm, called the triple loop method, with autonomous distributed agents has been proposed. The Improving initial Task Assignment and Avoiding Deadlock method (ITAAD) is a faster algorithm than the triple loop method. In this paper, we propose a new vehicle routing method for the ITAAD. Results of computational experiments show effectiveness of the proposed routing method.

The need to control CO 2 emissions, which are the main factor of global warming, is one of the most important problems in the 21st century. Therefore, the efficient supply and use of energy are indispensable. We have studied distributed energy management systems (DEMSs), in which we target to optimal plans that minimize costs through electrical and thermal energy trading under CO 2 emissions regulation. Previously, a trading method in which the Market Oriented Programming (MOP) is applied to DEMSs was proposed. However, this trading method can be used in the DEMSs consisted of a single consumer and several producers. In this paper, extending this method, we propose a trading method that can be used in DEMSs which consist of several consumers and several producers. Experimental results show that the method is effective in the DEMSs with several consumers and several producers.

A control of CO2 emissions which is the main factor of global warming is one of the most important problems in the 21st century about preservation of earth environment. Therefore, efficient supply and use of energy are indispensable. We have proposed distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both of costs and CO2 emissions through electrical and thermal energy trading. A DEMS consists of the plural entities that seek their own economic profits. In this paper, we propose a trading method that gives competitive equilibrium resource distribution by applying the market-oriented programming (MOP) to DEMSs.

Control of CO2 emissions, which are the main factor causing global warming, is one of the most important problems in the 21st century for the preservation of the earth's environment. Therefore, efficient supply and use of energy are indispensable. We have proposed distributed energy management systems (DEMS), which are intended to obtain optimal plans that minimize both costs and CO2 emissions by electrical and thermal trading. In this paper we evaluate trading methods for the DEMS through computational experiments. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(6): 32–40, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10203

The expansion of the renewable energy introduction is examined as measures for controlling global warming. Wind power generation is expected as effective power resource, but the negative impact from the difficulty of an unstable output is concerned. In recent years, WT generation with contract of cut-of with shorting adjusting power and with rechargeable battery for stabilizing control are examined, but the introduction has not been accelerated yet because there is an influence in WT generation entrepreneur's business. In this paper, we make a brief summary of relation between the fluctuation of wind power generation and stability of electric power operation, and two types of approach; cut-off contract and stabilization using rechargeable battery. For the stabilization using battery, there are two methods, one is reduction control and the other is constant control. We propose a new control method for constant control based on profit optimization considering WT generation forecast and its risk of deviation. We also propose the estimation method for the .limitation of battery installation. Simulation results show the efficiency of our proposed methods.

Petri nets are known as a modeling language for concurrent and distributed systems. In recent years, various object-oriented Petri nets were proposed, and we are proposing a kind of object-oriented Petri nets, called multi agent nets (MANs). In this letter, we consider the reachability analysis of MANs. We propose an algorithm for generating an abstract state space of a multi agent net, and report results of computational experiments.

Using a very simple neuronal model, it was shown that very slow and chaotic spiking appeared near the Hopf bifurcation point. Noise effect on the slow spiking was studied in detail and various interesting phenomena such as noise-induced spiking variability, deceleration and acceleration effects were presented.

Abatement of CO2 emission is one of the most important issues in the 21st century regarding preservation of the earth environment. This paper addresses a utility operations planning problem for distributed energy management systems (DEMSs), where we are to obtain optimal plans that minimize both costs and CO2 emissions. A DEMS consists of multiple entities that seek their own economic profits. In this paper, we give a mathematical formulation of the utility operations planning problem for each entity, and propose an energy trading market, which utlizes a multi-attribute auction protocol in order to deal with both a price and a CO2 emission rate. Experimental results show that collaboration among entities through the market provides a more profitable plan for each entity and abatement of CO2 emission is also achieved. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 54–63, 2008; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/eej.20418

For mission-critical and safety-critical systems such as medical, financial, or administrative information systems, a secure and reliable storage system is indispensable. The main purpose of our research is to develop a highly secure and highly reliable storage system. We have proposed a storage system that utilizes a secret sharing scheme. The storage system is called the Secret Sharing Storage System. So far, we have developed a prototype of the storage system. In this paper, we propose an automatic repair mechanism, and an interval decision method for this system.

A method for synthesizing feedback control logic for live and safe marked graphs has been given by Holloway and Krogh. The method strongly depends on the structure of marked graphs, and thus it has not been extended to wider classes. This paper considers the same problem of synthesizing the maximal permissive feedback control for a special condition by using unfoldings. Structural characteristics of unfoldings are similar to that of marked graphs. Transforming a Petri net to an unfolding allows us to apply the Holloway's approach to general bounded Petri nets.

The power supply for high intensity synchrotron magnet draws large amount of power from utility network. The JHF 50-GeV main ring will require 104 MW of total active power and 28.8 MW of dissipation power by estimation. Moreover, the charging and discharging cycle is repeated with 3.64 s of the cycle time at the initial operation, and the repeating frequency will be raised up by twice in future. Taking this situation into consideration, energy storage system using adjustable speed type flywheel and IGBT power converter are studied in the JHF project. In this paper, the power supply using SMES is proposed. The power supply can absorb the fluctuation of active and reactive power caused by charging and discharging the synchrotron magnet. The system is composed of current source ac/dc converter, chopper circuits and superconducting magnets. The chopper circuits for superconducting magnets and synchrotron magnets can be connected to the same dc bus of the power supply and this feature can reduce the power rating of ac/dc converters.

The effect of noise on the period of the van der Pol oscillator forced by a sinusoidal signal is analyzed in detail. The dynamics of the forced nonlinear oscillator with noise is described by the evolution of probability densities by a Markov operator. The oscillator shows a 1:1 phase-locked oscillation whose period is equal to the period of the sinusoidal forcing when the forcing is sufficiently strong. Noise modulates the oscillator's period as expected, but we show that this modulation is not uniform; the period of the oscillator changes drastically at a certain strength of noise. Thus this noise-induced breakdown of the phase locking can be considered as a stochastic bifurcation. The breakdown of stochastic phase-locking or the stochastic bifurcation is also analyzed from the viewpoint of the spectra of the Markov operator.

This paper presents a method to compensate voltage sags with minimum energy injection for a series-connected voltage restorer using a micro-SMES. A circuit for extracting the fundamental symmetrical components from sag voltages and a minimum energy injection algorithm is described. Simulations of voltage sag compensation have been carried out using PSCAD/EMTDC for various faults. The simulation results confirm the validity of the proposed method and show the possibility of reducing the size of energy storage devices. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 70–80, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10047

The Hodgkin–Huxley equations with a slight modification are investigated, in which the inactivation process (h) of sodium channels or the activation process of potassium channels (n) is slowed down. We show that the equations produce a variety of action potential waveforms ranging from a plateau potential, such as in heart muscle cells, to chaotic bursting firings. When h is slowed down – differently from the case of n variable being slow – chaotic bursting oscillations are observed for a wide range of parameter values although both variables cause a decrease in the membrane potential. The underlying nonlinear dynamics of various action potentials are analyzed using bifurcation theory and a so-called slow–fast decomposition analysis. It is shown that a simple topological property of the equilibrium curves of slow and fast subsystems is essential to the production of chaotic oscillations, and this is the cause of the large difference in global firing characteristics between the h-slow and n-slow cases.