Control of complex nonlinear dynamic rational systems

© 2018 Quanmin Zhu et al. Nonlinear rational systems/models, also known as total nonlinear dynamic systems/models, in an expression of a ratio of two polynomials, have roots in describing general engineering plants and chemical reaction processes. The major challenge issue in the control of such a system is the control input embedded in its denominator polynomials. With extensive searching, it could not find any systematic approach in designing this class of control systems directly from its model structure. This study expands the U-model-based approach to establish a platform for the first layer of feedback control and the second layer of adaptive control of the nonlinear rational systems, which, in principle, separates control system design (without involving a plant model) and controller output determination (with solving inversion of the plant U-model). This procedure makes it possible to achieve closed-loop control of nonlinear systems with linear performance (transient response and steady-state accuracy). For the conditions using the approach, this study presents the associated stability and convergence analyses. Simulation studies are performed to show off the characteristics of the developed procedure in numerical tests and to give the general guidelines for applications

Review of rational (total) nonlinear dynamic system modelling, identification, and control

© 2013 Taylor & Francis. This paper is a summary of the research development in the rational (total) nonlinear dynamic modelling over the last two decades. Total nonlinear dynamic systems are defined as those where the model parameters and input (controller outputs) are subject to nonlinear to the output. Previously, this class of models has been known as rational models, which is a model that can be considered to belong to the nonlinear autoregressive moving average with exogenous input (NARMAX) model subset and is an extension of the well-known polynomial NARMAX model. The justification for using the rational model is that it provides a very concise and parsimonious representation for highly complex nonlinear dynamic systems and has excellent interpolatory and extrapolatory properties. However, model identification and controller design are much more challenging compared to the polynomial models. This has been a new and fascinating research trend in the area of mathematical modelling, control, and applications, but still within a limited research community. This paper brings several representative algorithms together, developed by the authors and their colleagues, to form an easily referenced archive for promotion of the awareness, tutorial, applications, and even further research expansion

Enhanced Biometrics-based Remote User Authentication Scheme Using Smart Cards

Authentication and key exchange are fundamental techniques for enabling secure communication over mobile networks. In order to reduce implementation complexity and achieve computation efficiency, design issues for efficient and secure biometrics-based remote user authentication scheme have been extensively investigated by research community in these years. Recently, two well-designed biometrics-based authentication schemes using smart cards are introduced by Li and Hwang and Li et al., respectively. Li and Hwang proposed an efficient biometrics-based remote user authentication scheme using smart card and Li et al. proposed an improvement. The authors of both schemes claimed that their protocol delivers important security features and system functionalities, such as without synchronized clock, freely changes password, mutual authentication, as well as low computation costs. However, these two schemes still have much space for security enhancement. In this paper, we first demonstrate a series of vulnerabilities on these two schemes. Then, an enhanced scheme with corresponding remedies is proposed to eliminate all identified security flaws in both schemes

Effect of transcutaneous auricular vagus nerve stimulation on impaired glucose tolerance: a pilot randomized study

Background: Impaired glucose tolerance (IGT) is a pre-diabetic state of hyperglycemia that is associated with insulin resistance, increased risk of type II diabetes, and cardiovascular pathology. Recently, investigators hypothesized that decreased vagus nerve activity may be the underlying mechanism of metabolic syndrome including obesity, elevated glucose levels, and high blood pressure. Methods: In this pilot randomized clinical trial, we compared the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) and sham taVNS on patients with IGT. 72 participants with IGT were single-blinded and were randomly allocated by computer-generated envelope to either taVNS or sham taVNS treatment groups. In addition, 30 IGT adults were recruited as a control population and not assigned treatment so as to monitor the natural fluctuation of glucose tolerance in IGT patients. All treatments were self-administered by the patients at home after training at the hospital. Patients were instructed to fill in a patient diary booklet each day to describe any side effects after each treatment. The treatment period was 12 weeks in duration. Baseline comparison between treatment and control group showed no difference in weight, BMI, or measures of systolic blood pressure, diastolic blood pressure, fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG), or glycosylated hemoglobin (HbAlc). Results: 100 participants completed the study and were included in data analysis. Two female patients (one in the taVNS group, one in the sham taVNS group) dropped out of the study due to stimulation-evoked dizziness. The symptoms were relieved after stopping treatment. Compared with sham taVNS, taVNS significantly reduced the two-hour glucose tolerance (F(2) = 5.79, p = 0.004). In addition, we found that taVNS significantly decreased (F(1) = 4.21, p = 0.044) systolic blood pressure over time compared with sham taVNS. Compared with the no-treatment control group, patients receiving taVNS significantly differed in measures of FPG (F(2) = 10.62, p < 0.001), 2hPG F(2) = 25.18, p < 0.001) and HbAlc (F(1) = 12.79, p = 0.001) over the course of the 12 week treatment period. Conclusions: Our study suggests that taVNS is a promising, simple, and cost-effective treatment for IGT/ pre-diabetes with only slight risk of mild side-effects

Adaptive synchronised tracking control for multiple robotic manipulators with uncertain kinematics and dynamics

© 2014 Taylor & Francis. In this study, a new adaptive synchronised tracking control approach is developed for the operation of multiple robotic manipulators in the presence of uncertain kinematics and dynamics. In terms of the system synchronisation and adaptive control, the proposed approach can stabilise position tracking of each robotic manipulator while coordinating its motion with the other robotic manipulators. On the other hand, the developed approach can cope with kinematic and dynamic uncertainties. The corresponding stability analysis is presented to lay a foundation for theoretical understanding of the underlying issues as well as an assurance for safely operating real systems. Illustrative examples are bench tested to validate the effectiveness of the proposed approach. In addition, to face the challenging issues, this study provides an exemplary showcase with effectively to integrate several cross boundary theoretical results to formulate an interdisciplinary solution

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO_2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction (XRD). The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm(2) for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively

Electrochim. Acta

PbO2 electrodes doped with rare earth oxides (Re-PbO2), including Er2O3,.Gd2O3, La2O3 and CeO2, were prepared by anodic codeposition in order to investigate the effect of rare earth oxide dopants on the properties of PbO2 electrodes. The physicochernical properties of the Re-PbO2 electrodes were analyzed by spectral methods and electrochemical measurements. The surface morphology of the Re-PbO2 electrodes held the characteristics of the dopants and the crystal grain of PbO, The crystal structure of the PbO2 electrodes was also influenced by doping with different rare earth oxides. The presence of Er,03 and La,03 in the PbO2 films could enhance the direct anodic oxidation, which was helpful to mineralize 4-chlorophenol. The 4-chlorophenol decay on the Re-PbO2 electrodes was analyzed and good fitting was found using the relation for the pseudo-first order reaction. Of the electrodes examined, the Er-PbO2 electrode exhibited the best performance for the degradation of 4-chlorophenol. The removal rates of COD and 4-chlorophenol during the 9 h electrolysis at a current density of 20 mA cm(-2) were 80.7 and 100%, respectively, with the current efficiency being 16.0-10.1%. (C) 2007 Elsevier Ltd. All rights reserved.PbO2 electrodes doped with rare earth oxides (Re-PbO2), including Er2O3,.Gd2O3, La2O3 and CeO2, were prepared by anodic codeposition in order to investigate the effect of rare earth oxide dopants on the properties of PbO2 electrodes. The physicochernical properties of the Re-PbO2 electrodes were analyzed by spectral methods and electrochemical measurements. The surface morphology of the Re-PbO2 electrodes held the characteristics of the dopants and the crystal grain of PbO, The crystal structure of the PbO2 electrodes was also influenced by doping with different rare earth oxides. The presence of Er,03 and La,03 in the PbO2 films could enhance the direct anodic oxidation, which was helpful to mineralize 4-chlorophenol. The 4-chlorophenol decay on the Re-PbO2 electrodes was analyzed and good fitting was found using the relation for the pseudo-first order reaction. Of the electrodes examined, the Er-PbO2 electrode exhibited the best performance for the degradation of 4-chlorophenol. The removal rates of COD and 4-chlorophenol during the 9 h electrolysis at a current density of 20 mA cm(-2) were 80.7 and 100%, respectively, with the current efficiency being 16.0-10.1%. (C) 2007 Elsevier Ltd. All rights reserved