A design of a strongly stable generalized predictive control using coprime factorization approach

This paper proposes a new generalized predictive control (GPC) having new design parameters. In selecting the design parameters, the controller becomes a strongly stable GPC, that is, not only the closed-loop system is stable, but also the controller itself is stable. The parameters are introduced by applying the coprime factorization approach and comparing Youla parametrization of stabilizing compensators to the controller by the standard GPC</p

Dicke Superradiance in a magnetoplasma

We present theoretical results for superradiance, i.e. the collective coherent decay of a radiating system, in a semiconductor heterostructure under a strong quantizing magnetic field. We predict a strong peak (`Dicke-peak') in the emission intensity as a function of time, which should be observable after a short initial excitation of electrons into the conduction band. This peak has a characteristic dependence on the magnetic field and should be observable on sub-picosecond time scales. Furthermore, pumping of electrons and holes into the systems at a rate T leads to a novel kind of oscillations with frequency $\sim \sqrt{T}$ in the limit of the lowest Landau level.Comment: Proc. of HCIS-11, Kyoto(Japan), July 19-23 1999. To appear in Physica

Antitrust Analysis of B2B Transaction

B2B is a business-to-business market place that uses internet to connect each other business. It has gotten a lot more attention recently in Japan as well as in the U.S. because it is possible to lower the procurement costs of raw material and accomplish several procompetitive effects such as communication efficiencies. However, in spite of these pro transactional natures of B2B, it could also cause anticompetitive effects on market place. In other words, the fact that buyers communicate easily through the internet means they could easily form a cartel or conclude an agreement to restrain the free competition and it is easy to detect deviation from those agreements. There must have been buyers’ anticompetitive agreements long before B2B and these agreements were concluded without using the internet-based communication. However, the potential for B2B to aid buyers’ agreements is worth to get attention. Despite this importance, there have been little cases and studies concerning buyers’ agreement even in the U.S. and, in Japan, there have been neither cases nor the detail examination by the governmental agencies about buyers’ anticompetitive agreements. This is because traditionally sellers have had a strong bargaining power over purchasers. Therefore, little attention has been focused on anticompetitive effects which might be caused by buyers’ agreements. The internet, however, drastically changed the bargaining power balance between sellers and purchasers. It has made possible for purchasers to form a cartel to decrease the input purchased and lower the price through the web-based communication. The paper examines the competitive aspects of B2B from the view point of the antitrust law and analyzes oligopsony, that is, buyers’ collusion to exercise their market power to decrease the price of the products they are going to buy from suppliers by depressing the quantity of input purchased artificially. Drawing on microeconomic theory and antitrust law, the interdisciplinary work in the paper explores the implications of oligopsony, or buying power, for antitrust policy. The paper offers a systematic treatment of the topic, demonstrating that whether or not oligopsony power exists because of a dominant buyer or collusion among buyers, it can cause social welfare losses analogous to those occasioned by monopoly. The paper also discusses bilateral monopoly and offers a principled basis for distinguishing between socially desirable and undesirable cooperative buying. In addition, the paper analyzes the legal response to an oligopsony agreement in the U.S. as well as in Japan in order to examine how an oligopsony agreement should be treated. Further, the paper discusses tangential facts and circumstantial evidence to find an oligopsony agreement, because, in the antitrust practice, whether or not it is possible to find an agreement is sometimes the decisive point. The paper tries to provide the practical precepts to find an agreement which would be concluded on B2B

Antitrust Analysis of B2B Transaction

B2B is a business-to-business market place that uses internet to connect each other business. It has gotten a lot more attention recently in Japan as well as in the U.S. because it is possible to lower the procurement costs of raw material and accomplish several procompetitive effects such as communication efficiencies. However, in spite of these pro transactional natures of B2B, it could also cause anticompetitive effects on market place. In other words, the fact that buyers communicate easily through the internet means they could easily form a cartel or conclude an agreement to restrain the free competition and it is easy to detect deviation from those agreements. There must have been buyers’ anticompetitive agreements long before B2B and these agreements were concluded without using the internet-based communication. However, the potential for B2B to aid buyers’ agreements is worth to get attention. Despite this importance, there have been little cases and studies concerning buyers’ agreement even in the U.S. and, in Japan, there have been neither cases nor the detail examination by the governmental agencies about buyers’ anticompetitive agreements. This is because traditionally sellers have had a strong bargaining power over purchasers. Therefore, little attention has been focused on anticompetitive effects which might be caused by buyers’ agreements. The internet, however, drastically changed the bargaining power balance between sellers and purchasers. It has made possible for purchasers to form a cartel to decrease the input purchased and lower the price through the web-based communication. The paper examines the competitive aspects of B2B from the view point of the antitrust law and analyzes oligopsony, that is, buyers’ collusion to exercise their market power to decrease the price of the products they are going to buy from suppliers by depressing the quantity of input purchased artificially. Drawing on microeconomic theory and antitrust law, the interdisciplinary work in the paper explores the implications of oligopsony, or buying power, for antitrust policy. The paper offers a systematic treatment of the topic, demonstrating that whether or not oligopsony power exists because of a dominant buyer or collusion among buyers, it can cause social welfare losses analogous to those occasioned by monopoly. The paper also discusses bilateral monopoly and offers a principled basis for distinguishing between socially desirable and undesirable cooperative buying. In addition, the paper analyzes the legal response to an oligopsony agreement in the U.S. as well as in Japan in order to examine how an oligopsony agreement should be treated. Further, the paper discusses tangential facts and circumstantial evidence to find an oligopsony agreement, because, in the antitrust practice, whether or not it is possible to find an agreement is sometimes the decisive point. The paper tries to provide the practical precepts to find an agreement which would be concluded on B2B

Variable structure model reference adaptive control based on two-degree-of-freedom compensators scheme

In this paper, a variable structure model reference adaptive control system (MRACS) based an two-degree-of-freedom compensators scheme (2 DOF) is proposed. First, a MRACS with fixed compensator is constructed using the 2 DOF proposed in Masuda et al. (1994). Second, the fixed compensator is replaced by a switching compensator. The switching algorithm is determined in order that the estimated parameter can converge more rapidly. Since the Proposed method is based on the 2 DOF structure, the switching compensator works only when the parameter uncertainties are large. The boundedness of all signals in the closed-loop system and the convergence of the output error are proved. Finally, simulation results are illustrated to show the effectiveness of the proposed method </p

Transient performance improvement in dynamic certainty equivalent adaptive controllers by including a fixed compensator

We propose a modified Morse's dynamic certainty equivalent (DyCE) adaptive controllers in the continuous-time, single-input single-output linear time-invariant plant for the purpose of improving the transient performance. In the new scheme the additive feedback loop through a fixed compensator, which means a non-adaptive one, is included. Furthermore a design method for the fixed compensator is also given, and performance analysis for the proposed DyCE adaptive controller is examined in terms of the mean square tracking error criterion and the &Lscr;&#8734; tracking error bound. According to the results of the paper the transient performance can be improved arbitrarily by the properly designed fixed compensator. Finally a numerical example is illustrated in order to show the effectiveness of the proposed method </p

An extension of generalized minimum variance control for multi-input multi-output systems using coprime factorization approach

This paper proposes a new generalized minimum-variance controller (GMVC) having new design parameters by using the coprime factorization approach for a multi-input multi-output (MIMO) case. The method is directly extended from a conventional GMVC and used to construct the controller; it needs to solve only one Diophantine equation as in the conventional method. In this paper, by using double-coprime factorization, a simple formula for the closed-loop system given by the parametrized controller is obtained; and using the formula, it is proved that the closed-loop characteristic from the reference signal to plant output is independent of the selection of the design parameters and the poles of the controller can be chosen by the design parameters without changing the closed-loop system</p