Optimal fast-response sliding-mode control for flexible-substrate measurement

In order to control bending radii of flexible substrates in displays, this paper presents an optimal fast-response sliding-mode control method. Maximum driving voltages are utilized in sliding-mode control based on a linear quadratic estimator. An optimal design for the threshold value and the reaching-law parameter are obtained by using a procedure of the fast-response regulation. Implementing the proposed method, this study measures electrical resistances for different widths of line patterns on polyethylene terephthalate/indium tin oxide substrates up to 11,000 bending times.     

State estimation for nonlinear systems under model uncertainties: a class of sliding-mode observers

This paper deals with the classical problem of state estimation, considering partially unknown, nonlinear systems with noise measurements. Estimation of both, state variables and unstructured uncertain term, are performed simultaneously. In order to transform the measured disturbance into system disturbance, an alternative system representation is proposed, which lead a more advantageous observer structure. The observer proposed contains a proportional-type contribution and a sliding term for the measurement of error, which provides robustness against noisy measurements and model uncertainties. Convergence analysis of the estimation methodology proposed is performed, analysing the equation of the dynamics of the estimation error; it is shown that the observer exhibits asymptotic convergence. Estimation of monomer concentration, average molecular weight, polydispersity and filtering of temperature in a batch stirred polymerization reactor illustrates the good performance of the observer proposed.     

Fault detection and isolation design for uncertain nonlinear systems based on full-order,reduced-order and high-order high-gain sliding-mode observers

This paper considers the observer-based fault detection and isolation design problems when the observer matching condition is not satisfied. Based on the relative degree concept, an auxiliary output vector that may satisfy the observer matching condition is constructed. Since the auxiliary output vector contains unknown information, we use a high-order high-gain sliding-mode observer to exactly estimate not only the auxiliary outputs, but also their derivatives in a finite time. Then, an adaptive robust full-order observer is developed to serve as an actuator fault detection observer. For the actuator fault reconstruction purpose, a reduced-order observer is proposed to estimate the system states even if there are some actuator faults and an actuator fault reconstruction method is provided to reach the fault isolation purpose. A numerical simulation example is used to illustrate the effectiveness of the proposed methods.     

Sliding-mode observers for nonlinear systems with unknown inputs and measurement noise

This paper deals with the design of observers for Lipschitz nonlinear systems with not only unknown inputs but also measurement noise when the observer matching condition is not satisfied. First, an augmented vector is introduced to construct an augmented system, and an auxiliary output vector is constructed such that the observer matching condition is satisfied and then a high-gain sliding mode observer is considered to get the exact estimates of both the auxiliary outputs and their derivatives in a finite time. Second, for nonlinear system with both unknown inputs and measurement noise, an adaptive robust sliding mode observer is developed to asymptotically estimate the system’s states, and then an unknown input and measurement noise reconstruction method is proposed. Finally, a numerical simulation example is given to illustrate the effectiveness of the proposed methods.     

Microbial specific growth rate control via MRAC method

A problematic feature in most fermentation processes is that on-line measurement of the most important biological process variables, the concentration of the bio-mass and its specific growth rate, cannot be directly measured. An approach for estimating these biological variables and for controlling the specific growth rate in a continuous flow bioprocess of a stirred tank reactor is presented and analysed. The goal in the control is to get the specific growth rate to track the rate of a given reference model, A dynamic model for the specific growth rate is obtained from the general growth and substrate consumption model. The structure of the rate model is then applied in the reference model structure. The methodology studied is based on two issues, joint state and parameter estimation and direct adaptive control. From the theoretical viewpoint, this forms a combination of indirect and direct adaptive control. The structure of the control law is justified by the structure of the law obtained for known fixed parameters. Convergence of the estimation scheme and of the adaptive control scheme are demonstrated via Lyapunov's method, and separately. The choice of the appropriate Lyapunov function results in a Pl-type controller with the gains as the parameters to be adjusted by the user. A simulation study based on Monod's model and time-varying model parameters and subject to measurement noise shows the feasibility and robustness of the adaptive control methodology developed for this non-linear process.     

Sliding mode observers for nonlinear models with unbounded noise and measurement uncertainties

This work extends the applicability of variable structure observers designed for nonlinear systems in two ways. First, it is proved that these observers using a boundary-layer scheme can be applied to system models described by Ito differential equations, resulting in almost sure and mean square exponential estimation error. Second, the use of variable structure observers is extended to nonlinear measurement models containing disturbance effects. Also, a novel approach for obtaining the required parameters in the observer design is provided. Finally, two examples are given to illustrate the application and favorable convergence properties of these generalizations.     

Nonlinear observers for spacecraft attitude estimation in case of yaw angle measurement absence

This paper provides a brief presentation and a useful comparison between two nonlinear observers Extended Kalman Filter (EKF) and sliding mode observer (SMO). Both can be used for moderate-accuracy attitude determination systems for Low Earth Orbit (LEO) Earth-pointing spacecraft (s/c), which is typically achieved using Gyroscopes, Earth, and Sun sensors for attitude sensing. The use of these observers provides a substitute for the yaw data in case of the s/c eclipse periods or limited field of views. The nonlinear observability for this system is analytically investigated via the calculation of Lie derivatives to check the possibility of the system states estimation. The performances of both observers are presented, the SMO stability is proved and the SMO enhanced estimates are shown by simulation.     

Construct specific coupling measurement for C++ software

Studies which consider the extent to which the encapsulation of a class is weakened by direct access to its hidden members (such as through the use of the friend construct in C++) are scarce, and those that do exist are based on metric suites where the enabling mechanism of the coupling is ignored. This can lead to conclusions of limited construct validity where incorrect causes of coupling are suggested.In this paper a suite of software metrics which measure the amount of coupling enabled by different C++ programming language constructs (such as friendship and inheritance) are proposed. The metrics presented are based on a formal data model which can be easily adapted for other OO languages. This formal approach removes the scope for ambiguity in the metric definitions. These metrics provide a more accurate reflection of the causative agents of coupling in Object Oriented Systems and their utility is illustrated in an empirical study towards the end of the paper.     

Decoherence dynamics of geometric measure of quantum discord and measurement induced nonlocality for noninertial observers at finite temperature

Quantum discord quantifies the total non-classical correlations in mixed states. It is the difference between total correlation, measured by quantum mutual information, and the classical correlation. Another step forward towards the quantification of quantum discord was by Daki? et al. (Phys Rev Lett 105:190502, 2010) who introduced the geometric measure of quantum discord (GMQD) and derived an explicit formula for a two-qubit state. Recently, Luo and Fu (Phys Rev Lett 106:120401, 2011) introduced measurement-induced nonlocality (MIN) as a measure of nonlocality for a bipartite quantum system. The dynamics of GMQD is recently considered by Song et al. (arXiv: quant/ph.1203.3356) and Zhang et al. (Eur Phys J D 66:34, 2012) for inertial observers. However, the topic requires due attention in noninertial frames, particularly, from the perspective of MIN. Here I consider $X$ -structured bipartite quantum system in noninertial frames and analyze the decoherence dynamics of GMQD and MIN at finite temperature. The dynamics under the influence of amplitude damping, depolarizing and phase flip channels is discussed. It is worth-noting that initial state entanglement plays an important role in bipartite states. It is possible to distinguish the Bell, Werner and general type initial quantum states using GMQD. Sudden transition in the behaviour of GMQD and MIN occurs depending upon the mean photon number of the local environment. The transition behaviour disappears for larger values of $\bar{n},$ i.e. $\bar{n}>0.3.$ It becomes more prominent, when environmental noise is introduced in the system. In the presence of environmental noise, as we increase the value of acceleration $r$ , GMQD and MIN decay due to Unruh effect. The effect is prominent for the phase flip and amplitude damping channels. However, in case of depolarizing channel, no sudden change in the behaviour of GMQD and MIN is observed. The environmental noise has stronger affect on the dynamics of GMQD and MIN as compared to the Unruh effect. Furthermore, Werner like states are more robust than General type initial states at finite temperature.     

Monitoring of droplet growth with nano-litre resolution for liquid flow rate, level or surface tension measurement

The determination of small liquid volumes and their changes over a period of time is a measuring problem with increasing importance considering the growing market of micro-systems. In this paper, experimental investigations are described which aim to observe the growth of droplets at the end of a micro-channel, such as a cannula or capillary. The main focus of the work lies on the calculation of flow rates below 1 ml/h. Furthermore, the potential of the measuring equipment for liquid level and surface tension measurement is described.     

Non-linear sliding-mode controller and objective function for surge tanks

A non-linear feedback controller is proposed for the ‘averaging’ control of surge tanks subject to step flowrate disturbances. The controller operates by discont-inuously switching between two non-linear feedback rules. A switching function is constructed that results in a sliding-mode that brings the system to a steady state with a finite, bounded, and ultimately monotonic response. The properties of the controller are thoroughly described using a phase plane analysis. The effects of transducer errors are analysed and a controller tuning procedure is described. It is shown that a liquid volume setpoint can be introduced if the relative volume measurement error is less than 26.42 %. A simplified implementation using a piece-wise linear switching function is also proposed for which simulations and phase plane analysis show little performance degradation. Finally, it is shown that (he idealized ‘Ramp Controller’ proposed by McDonald el al. (1986) can be derived from a continuous and differentiable objective function. The objective function is constructed for the maximum rate of change of outlet flowrate by formulating and solving an inverse optimal control problem.     

Microcantilever-based weather station for temperature,humidity and flow rate measurement

The current study develops a new process for the fabrication of Pt resistor temperature detectors (RTDs), cantilevers covered with a water-absorbent polyimide layer for humidity measurement and the bending-up of cantilevers to determine the flow rate. Pt RTDs are fabricated on the silicon substrate. The temperature measurement is based on the linear resistance variations when temperature changes. The polyimide layer is spun on the cantilever to form a humidity sensing layer. A variation in humidity causes moisture-dependent bending of the micro-cantilever, which changes the measured resistance of the resistor on the micro-cantilever. The same type of micro-cantilever, without spinning on polyimide, is used to form an anemometer. It is found that the cantilever bends slightly upward as a result of the released residual stress induced in the beam during the fabrication. When wind passes over the cantilever beam, a small deformation occurs. Variations in the flow rate can therefore be determined by measuring the changes in resistance caused by the beam deflection, using a LCR meter.     

Parallelotopic and practical observers for non-linear uncertain systems

For a class of dynamical systems, with uncertain non-linear terms considered as unknown inputs, we give suffcient conditions for observability. We show also that there does not exist any exact observer independent of the unknown inputs. Under the additional assumption that the uncertainty is bounded, we build practical observers whose error converges exponentially towards an arbitrarily small neighbourhood of the origin. Under the hypothesis that bounds are available for the uncertain terms, we build parallelotopic observers providing time-varying bounds for the state variables, even when the system is not observable for unknown inputs. These results are illustrated with a biological model of a structured population.     

低速率语音编解码专用处理器设计

本文给出一种基于编码速率600bps的高质量声码器算法的专用处理器设计。介绍了语音编解码算法原理,专用处理器的体系结构,汇编器的开发和算法的移植。采用软硬件协同设计的方法,大大降低了算法的存储复杂度和运算复杂度,并在电路中验证了声码器地正确性。     

Nonlinear observers for a class of biological systems: applicationto validation of a phytoplanktonic growth model

The authors construct nonlinear observers in order to discuss the validity of biological models. They consider a class of systems including many classical models used in biological modeling. They formulate the nonlinear observers corresponding to these systems and prove the conditions necessary for their exponential convergence. They apply these observers on the well-known Droop model which describes the growth of a population of phytoplanktonic cells. The validity of this model is discussed based on the performance of the observers working on experimental data     

Global output feedback control of feedforward nonlinear time-delay systems with unknown growth rate and unknown measurement sensitivity

This paper discusses the problem of global state regulation via output feedback for a class of feedforward nonlinear time-delay systems with unknown measurement sensitivity. Different from previous works, the nonlinear terms are dominated by upper triangular linear unmeasured (delayed) states multiplied by unknown growth rate. The unknown growth rate is composed of an unknown constant, a power function of output, and an input function. Furthermore, due to the measurement uncertainty of the system output, it is more difficult to solve this problem. It is proved that the presented output feedback controller can globally regulate all states of the nonlinear systems using the dynamic gain scaling technique and choosing the appropriate Lyapunov–Krasovskii functionals.     

Fuzzy observers for anaerobic WWTP: Development and implementation

In this paper a set of fuzzy observers for anaerobic digestion is proposed to estimate variables difficult to measure in a completely stirred tank reactor. First, a mathematical model for the process is stated and experimentally validated. Then, a methodology based on principal components analysis is developed to select fuzzy variables, which allow the local observers to be adequately activated. The active local observers are interpolated using the Takagi–Sugeno approach, in order to recover the non-linear behaviour; to ensure their adequate performance, the respective stability analysis is included. The whole estimation scheme is validated via simulations and tested in a real process.