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To a non-minimum phase nonlinear system, it was supposed that, if there is an output feedback control that stabilizes the auxiliary system, then there is an output feedback that stabilizes the original system. The existing methods base designing output feedback for non-minimum phase nonlinear system on the hypothesis that there exists output feedback for auxiliary system. However, the auxiliary system could be unobservable. Alternatively, this study aims to create a way to design output feedback for auxiliary systems in unobservable situation. An output state is constructed in the last equation of auxiliary system, which artificially makes the internal dynamics of the auxiliary system observable. Then, a cascade high-gain observer is designed for the auxiliary system, consisting of an extended high-gain observer for external dynamics and a high-gain observer for internal dynamics of the auxiliary system. Therefore, the output feedback control for auxiliary system can be designed via the cascade high-gain observer and a state feedback. Finally, the proposed method is demonstrated by an academic example and an inverted pendulum on a cart in the simulation. [ABSTRACT FROM AUTHOR]

Humans acquire much of their knowledge from the testimony of other people. An understanding of the way that information can be conveyed via gesture and vocalization is present in infancy. Thus, infants seek information from well-informed interlocutors, supply information to the ignorant, and make sense of communicative acts that they observe from a third-party perspective. This basic understanding is refined in the course of development. As they age, children's reasoning about testimony increasingly reflects an ability not just to detect imperfect or inaccurate claims but also to assess what inferences may or may not be drawn about informants given their particular situation. Children also attend to the broader characteristics of particular informants-their group membership, personality characteristics, and agreement or disagreement with other potential informants. When presented with unexpected or counterintuitive testimony, children are prone to set aside their own prior convictions, but they may sometimes defer to informants for inherently social reasons. [ABSTRACT FROM AUTHOR]

A positioning control system for a magnetic head in hard disk drives (HDDs) is a sampled-data control system that has a sampler and a hold. As a result, the control system has unobservable oscillations in a repeatable run-out (RROs) whose frequencies are above the Nyquist frequency. These unobservable oscillations may lead to destruction of user data in HDDs. To solve this problem, this paper presents a minimization method for the unobservable oscillation in the RROs. This minimization method focuses on a relationship between RRO frequencies and a sampling frequency of the sampled-data control system. To estimate amounts of the unobservable RROs beyond the Nyquist frequency, this study employs two types of unobservable magnitudes: a maximum value based magnitude, and a root-mean-square value based magnitude. By using these unobservable magnitudes, we can choose the best suited sampling frequency to minimize the unobservable oscillations in RROs of HDDs. [ABSTRACT FROM AUTHOR]

Abstract: Economou and Kanta (2008) [4] considered equilibrium customer strategies in the observable M/M/1 queue with an unreliable server. It is assumed that the server alternates between on and off periods. Upon arrival, the customers can observe the queue length and will decide whether to join or balk the system according to the information about the server’s state based on a linear reward-cost structure. In this paper, the corresponding unobservable cases in which the queue length is unobservable to arriving customers are investigated. The mixed equilibrium balking strategies are derived in two cases, according to the information on the server’s state. Numerical examples are presented to illustrate the effect of the information levels on the behavior of the customers. [Copyright &y& Elsevier]

Abstract: To improve reliability in hard disk drives, we proposed an estimation method for unobservable settling vibration in head-positioning control systems. Our proposed method uses both observability and excitability of mechanical vibrations in settling time of a track-seeking control. To see the observability, we employed the estimation method of unobservable amplitude of oscillations caused by mechanical resonances. To see the excitability, we also employed the Shock Response Spectrum (SRS) analysis that can handle the transient characteristics of mechanical vibrations. Simulations and experiments results on the track-seeking control showed that the results of our proposed method were good approximate solutions of the unobservable settling vibrations. This means that we can estimate the risk of the unobservable settling vibrations which may lead to destruction of user data in hard disk drives by using the proposed method. As a result, we can chose the best suited solution to avoid unobservable vibrations in the head-positioning control systems. [Copyright &y& Elsevier]

We provide a method for constructing local observers for some nonlinear systems around a critical point where the linearization is not observable or not detectable. Two examples are provided to illustrate the results of the paper. [Copyright &y& Elsevier]

A review of economic policy towards pollution control is presented which shows that appropriate measures will depend on whether the pollution is of a point or a diffuse nature. Regulation of the former is comparatively straightforward, with command and control and market instruments the tools of pollution control. The advantages and disadvantages of each measure are outlined. However, the inability to monitor emissions at source, precludes the application of point source measures in the case of diffuse source pollution. Instead, methods are required which overcome the need for direct monitoring. Several suggestions that propose ways of achieving this have been put forward and these are described. It is concluded that appropriate measures depend on the particular features of the problem and it is not possible to offer a blanket solution to either point sources or diffuse pollution. [Copyright &y& Elsevier]