Abstract:In the revised paper, we have highlighted the changes made in Blue FONT. This paper presents a combined parameter and state estimation algorithm for a bilinear system described by its observer canonical state space model based on the hierarchical identification principle. The Kalman filter is known as the best state filter for linear systems, but not applicable for bilinear systems. Thus, a bilinear state observer (BSO) is designed to give the state estimates using the extremum principle. Then a BSO based recursive least squares (BSO-RLS) algorithm is developed. For comparison with the BSO-RLS algorithm, by dividing the system into three fictitious subsystems on basis of the decomposition-coordination principle, a BSO based hierarchical least squares algorithm is proposed to reduce the computation burden. Moreover, a BSO based forgetting factor recursive least squares algorithm is presented to improve the parameter tracking capability. Finally, a numerical example illustrates the effectiveness of the proposed algorithms. IntroductionParameter estimation is a significant part in system identification, and has been widely used in system analysis [1][2][3], system modeling [4][5][6][7], and system control [8,9]. Since many industrial processes are complex and inherently nonlinear, nonlinear system identification has drawn much attention throughout the world [10][11][12]. The bilinear approach for modeling these complex processes are proven to be more precise than any other traditional linear models [13]. However, the nonlinear term existing in the bilinear model brings some challenges for bilinear system identification. During the past decades, much work has been carried out on parameter estimation for bilinear systems. For example, dos Santos et al. presented a subspace identification method for bilinear systems by treating the bilinear term as a second-order white noise process [14]. Larkowski et al. addressed the identification problem of the diagonal bilinear errors-in-variables system and extended the bias compensated least squares technique to bilinear systems [15]. Li et al. applied the polynomial transformation technique to obtain the equivalent input-output representation of the bilinear system and proposed the iterative algorithm for parameter estimation [16][17][18]. The recursive least squares (RLS) approach is known as the most commonly used estimation method among numerous different parameter estimation techniques. Although the RLS method offers a fast convergence rate, there exists several problems such as the increase in the computational burden and the decline in the tracking capability [19,20]. The hierarchical identification principle is applied to decompose a bilinear system into several subsystems Nonlinear filtering techniques have attracted much attention in signal processing [26,27] and have wide applications in many areas [28][29][30][31]. The classical Kalman filter (KF) is recognized as the best linear filter for linear systems under Gaussian noises. However, it is not suitable f...

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Silica coating can effective solve the stability issue of lead halide perovskite nanomaterials. However, it is difficult to achieve aqueous SiO2 coating on hydrophobic CsPbBr3 nanocrystals (NCs). In this paper,...

CsPbX3 perovskite quantum dots (QDs) have been receiving extensive attention in the fields of luminescence and photovoltaics. However, the bad stability of the CsPbX3 QDs limited their practical applications because of the inevitable factors including light, heat, and humidity. In this paper, a mechanical chemical synthesis method with no organic solvent (oleylamine and oleic acid) addition was used to grow inorganic CsPbX3 (X = Cl, Br, and I) QDs in situ in the hole of zeolitic imidazolate framework-8 (ZIF-8), thus improving the stability and resistance to ion exchange of CsPbX3 QDs. Due to the presence of CsPbX3 QDs in ZIF-8, the QDs were protected by the ZIF-8 matrix to impede luminescence degradation. The photoluminescence (PL) quantum yields of CsPbCl3/ZIF-8, CsPbBr3/ZIF-8, and CsPbI3/ZIF-8 composites were 51, 72, and 57%, respectively. Compared with the initial CsPbX3 QDs, the CsPbX3/ZIF-8 composites exhibited narrower emission spectra and stable PL, which can be maintained for 75 days under atmospheric conditions. The QDs with blue, green, and red emissions were created by controlling synthesis conditions. A green light-emitting diode (LED) with Commission Internationale de I′Eclairage (CIE) coordinates of (0.130, 0.746) and a white LED with CIE coordinates of (0.297, 0.299) were obtained. The lumen efficiency of the white LED device is 11.5 lm/W. ZIF-8 matrix encapsulation greatly improves the stability of CsPbX3 QDs, which makes them attractive in LED and optoelectronic device-related applications.