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Regime-switching models have been heavily studied recently, as they have some clear advantages of over other non-constant volatility model to resolve the so-called smirk effect displayed when constant volatility models are used to price financial derivatives such as options. However, due to the increased model complexity, the associated computational effort usually increases as well, particularly when they are used to price American-style options. In this paper, a novel computational approach based on integral equations is presented. A distinctive feature of our approach, in comparison with other numerical approaches, is that the coupled partial differential equations (PDEs) in a PDE system have been decoupled in the Fourier space, resulting in a completely decoupled integral equation for each economical states, and thus has greatly reduced computational effort. Some examples with preliminary results for a two-state regime-switching model are used to demonstrate our approach. [ABSTRACT FROM AUTHOR]

This paper deals with the observability and sensitivity analysis of the lightcurve measurement for use in the estimation of instantaneous pose (orientation) and shape geometry. Since several reflectance models exist that are typically used in obtaining a synthetic lightcurve measurement, they are compared to assess the observability or/and 'sensitivity' to determine the 'best model' for use. These measurement models are nonlinear with implicit and non-trivial dependency on the states; a numerical Jacobian as well as an unscented Kalman filter derived observation matrix are synthesized for each choice of the measurement model and compared. As the linearization is about an attitude (orientation) trajectory, distinct cases are considered to elaborate the results. For the cases evaluated here, it is shown that the attitude and shape/size can indeed be estimated from the lightcurve, but this is also dependent upon the initial conditions (subsequent attitude trajectory). Linear observability analysis of a discretized system is also performed with respect to the attitude states and shape/size parameters using the singular value decomposition of the observability matrix synthesized for a batch of measurements. The results are summarized for various initial conditions of the resident space object's attitude and angular velocity states. [ABSTRACT FROM AUTHOR]

In the conventional output voltage feedback loop design of an active power factor corrector (PFC), the bandwidth of the loop is limited to a frequency significantly lower than the input line voltage frequency. This is due to the fact that the compensator placed in the outputvoltage feedback loop is usually designed to have a narrow bandwidth in order to filter the voltage ripple of twice the line frequency coming from the PFC output dc voltage. This feedback loop is designed with this filtering effect because a relatively high ripple voltage would cause considerable distortion in the reference of the line current feedback loop. However, a low bandwidth voltage feedback loop would bring poor dynamic response which usually causes large overshoots and dips during load transient change. Therefore, a compromise is generally made for the traditional design of the output voltage feedback loop, which leads to an issue that both the steady and the dynamic behaviours of the PFC are not optimal. In this paper, mathematic model of the steady behaviour of a PFC with voltage ripple in the output-voltage feedback loop is studied using two parameters: the amplitude of the relative voltage ripple on the control output signal and its phase lag angle of the voltage feedback loop. On the basis of the analysis, a second-order voltage harmonic injection to the output-voltage feedback loop is used to eliminate the voltage harmonic components from the voltage feedback loop. Finally, the feasibility of the proposed second-order harmonic injection method was verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Electronic cash is an electronic form of currency, which allows the cash transactions over communication networks under privacy protections. However, it still has some aspects that have not been well studied. Known constructions suffer from at least one of the following limitations: (1) relying on a random oracle, (2) not supporting multiple bank setting and users dynamically joining or (3) prohibitively expensive. In this paper, we propose a new electronic cash system that avoids all these limitations. In other words, our system is anonymous against chosen-ciphertext attack (CCA) in the standard model, and supports multiple banks enrolling and users dynamically joining, which is achieved by the utilization of non-interactive zero-knowledge proof and dynamic group signature. Finally, in the standard model, a formal security proof is given to claim that our system has CCA anonymity, unforgeability, traceability and no double-spending. Compared with the existing systems, ours has advantages of both the efficiency and security. [ABSTRACT FROM AUTHOR]