1,079 research outputs found
Output Tracking Control for Fractional-Order Positive Switched Systems with Input Time Delay
No full textThe objective of this brief is to focus on the problem of output tracking control for a class of fractional-order positive switched systems via an observer-based controller method that combines equivalent-input-disturbance approach and Smith predictor. By employing Lyapunov theory together with average dwell-time approach, a new exponential stability criterion is derived in terms of linear matrix inequalities for the resulting closed-loop system. Based on the derived delay-dependent criterion, a design method of the proposed controller is then presented. The designed controller can assure that the output signals of the system trace the specified reference signals within the preferred neighborhood of the equilibrium. Furthermore, the solvability inclusive conditions for the proposed controller design of the considered system are established according to the state being available or not. Numerical simulation results are provided to demonstrate the strong disturbance rejection capability and the superiority of the proposed control design method over some existing ones
Mechanical characterisation of concrete beams filled with different amounts of nanosilica and coir-human hair fibre
No full textThe study concentrates on the cyclic behaviour of concrete grade M25 with the addition of
nanosilica powder and equal amounts of waste coir fibres and human hair. The results indicate that the improvement of cyclic flexural and number of cycles to failure, other than compressive, split tensile and static flexural properties, are effective and consistent up to a global 1.5% volume of the two waste fibres and 3% volume of nanosilica. Also crack patterns appear neater and suggest a
higher ductility of the material, up to this limit of content filler, indicating that to increase it further
work on the repeatability and consistency of introduction would be required
Adaptive reliable output tracking of networked control systems against actuator faults
No full textThis paper investigates the reliable adaptive observer-based output tracking control problem for a class of networked control systems subject to actuator faults and external disturbances via equivalent-input disturbance technique. Notably, the reliable control design based on adaptive mechanism is implemented to compensate the on-line actuator faults automatically and an observer-based controller is introduced through communication networks to drive the output of controlled plant to track the output of a reference model. Moreover, due to the effect of network-induced delays and packet dropouts in the controller-to-actuator channel, the inputs of controlled plant and observer-based tracking controller are updated in an asynchronous way. Then, based on the asynchronous characteristic, the resulting closed-loop networked control system is formulated with two interval time-varying delays for obtaining the required result. In particular, the equivalent-input disturbance approach improves the disturbance rejection performance and it does not require any prior knowledge of the disturbances. By constructing a suitable Lyapunov–Krasovskii functional and using free-weighting matrix approach, a new set of sufficient conditions for the solvability of the addressed problem is derived in terms of linear matrix inequalities. At last, the proposed result is validated through two numerical examples and also a comparison study is presented which shows the effectiveness of the developed control scheme over some existing conventional control schemes
Non-fragile fault-tolerant control for nonlinear Markovian jump systems with intermittent actuator fault
No full textThe non-fragile fault-tolerant control for a class of nonlinear Markovian jump systems with intermittent multiple actuator faults is addressed in this study. The nonlinearity in the considered system is assumed to satisfy sector constraint. Multiple Markov chains are introduced to model the multiple intermittent actuator faults, which is in a multiplicative form. To ensure the fault tolerance of the closed-loop system in the presence of potential controller perturbation, a new non-fragile fault-tolerant controller is designed, which can stabilize the resulting closed-loop system and further satisfy a prescribed performance index. After appropriately synthesizing the fault model that dominated by multiple Markov chains and the underlying nonlinear Markovian jump system, a set of sufficient conditions for the considered problem focusing on the controller design is derived with both known and partially known transition probabilities, where the controller can be determined via a convex optimization procedure. An example is given to illustrate the effectiveness of the proposed controller
Unified synchronization and fault‐tolerant anti‐disturbance control for synchronization of multiple memristor‐based neural networks
No full textThis work primarily concentrates on the design of fault-tolerant anti-disturbance control for synchronization of multiple memristor-based neural networks subject to time delay, matched and mismatched disturbances. Moreover, in the addressed network model, we consider parameter uncertainties and actuator faults. Firstly in order to estimate the matched disturbances generated by the exogenous system, a disturbance observer is devised. Whereas, the mismatched part is tackled by employing the mixed (Formula presented.) and passivity performance indexes. Subsequently, a unified controller is designed by incorporating error feedback control and the disturbance estimate. Further, with the assistance of Lyapunov stability theory and linear matrix inequality technique, an adequate criteria is procured to ascertain the required synchronization criteria for the assayed network model with the mixed (Formula presented.) and passivity performance indexes. Following this, by basing on the established conditions, the explicit form of the controller and observer gain matrices is obtained. In the end, a numerical example with simulation results is shown to confirm the potential and usefulness of the conclusions acquired from the theoretical analysis.This work primarily concentrates on the design of fault-tolerant anti-disturbance control for synchronization of multiple memristor-based neural networks subject to time delay, matched and mismatched disturbances. Moreover, in the addressed network model, we consider parameter uncertainties and actuator faults. Firstly in order to estimate the matched disturbances generated by the exogenous system, a disturbance observer is devised. Whereas, the mismatched part is tackled by employing the mixed Script capital H infinity and passivity performance indexes. Subsequently, a unified controller is designed by incorporating error feedback control and the disturbance estimate. Further, with the assistance of Lyapunov stability theory and linear matrix inequality technique, an adequate criteria is procured to ascertain the required synchronization criteria for the assayed network model with the mixed Script capital H infinity and passivi..
EID-based sliding mode investment policy design for fuzzy stochastic jump financial systems
No full textThis paper proposes a sliding mode investment policy design for nonlinear stochastic financial systems which can be represented by the well-known Takagi–Sugeno fuzzy model. When modeling the financial systems, it is more important to consider the unpredictable investment changes and worldwide unpredictable events which can be regarded as external disturbances. The equivalent-input-disturbance (EID) approach combined with sliding mode investment policy design is implemented to reject the unpredictable investment changes for having better investment. Moreover, the Luenberger state observer is constructed for the addressed financial system to estimate the unpredictable investment changes and worldwide unpredictable events. More precisely, a sliding mode investment policy design is developed by solving the obtained linear matrix inequality (LMI)-based constrained algorithm. Finally, the obtained results of the addressed fuzzy stochastic financial system are verified through numerical simulation to show efficiency of the proposed sliding mode investment policy design
A Robust Repetitive-Control Design for a Class of Uncertain Stochastic Dynamical Systems
No full textIn this brief, we study the problem of output tracking for continuous-time stochastic dynamical systems with parametric uncertainties and aperiodic disturbances by using a modified repetitive controller (MRC). More precisely, the MRC is obtained based on the equivalent input disturbance (EID) technique such that the closed-loop modified repetitive-control system is asymptotically stable in the presence of uncertainties and aperiodic disturbances. The main advantage of the proposed controller is that it can incorporate an EID estimator, which estimates and eliminates disturbances in the repetitive-control systems. Finally, simulation is conducted to reveal that the proposed controller can effectively reject the aperiodic disturbance, reduce the stochastic noise, and track the reference signal without steady-state error
Output tracking control design with anti-disturbance rejection for modified repetitive nonlinear control systems
No full textThis paper intends to analyse the disturbance rejection and output tracking control for a class of nonlinear control systems with disturbances. In this connection, we present a method that combines a proportional-integral observer and nonlinear-equivalent-input-disturbance estimator for superior disturbance rejection performance. Specifically, the nonlinear-equivalent-input-disturbance estimator comprises of equivalent-input-disturbance estimator and nonlinear feedback term, which is employed to estimate and reject the disturbances from the nonlinear system. Notably, the proportional-integral loop in the proportional-integral observer reduces the estimation inaccuracy of the nonlinear-equivalent-input-disturbance. Then the estimated disturbance is intertwined into the repetitive control input to compensate it efficiently. In order to obtain the required results, the proposed control system is converted into a two-dimensional modified repetitive control system to describe the learning and control actions. In particular, the proposed controller enables to adjust the gains directly to improve the learning and control performance and as a result, the tracking accuracy increases. Using a general Lyapunov–Krasovskii functional, singular value decomposition technique and linear matrix inequalities approach, a design algorithm for establishing proportional-integral observer and feedback gains is developed for the system under consideration. Finally, simulation results are given to illustrate the developed method's validity and superiority
sj-docx-1-pie-10.1177_09544089231207476 - Supplemental material for Can pretrained networks be used in fault diagnosis of monoblock centrifugal pump?
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089231207476 for Can pretrained networks be used in fault diagnosis of monoblock centrifugal pump? by Arun Balaji M, Naveen Venkatesh S, Sakthivel N R and Sugumaran V in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
Co-stimulatory molecules : genes to protein in autoimmune and inflammatory disorders
No full textCo‐stimulatory molecules are antigen‐independent generators of secondary signals which aid in maintaining the homeostasis of the immune system. The most extensively studied co‐stimulatory pathway is CD28/CTLA‐4, expressed on the T cells, interacting with CD80/CD86, expressed on the antigen presenting cells (APC). The interaction between CD28 and CD80/CD86 initiates the activation of T cells, whereas subsequent interaction between CTLA‐4 and CD80/CD86 inhibits the activated T lymphocytes. Also, there exist several other co‐stimulatory pathways. The co‐stimulatory molecules analyzed, in this study are B7H3, CD28, CD80, CD86, CTLA‐4, PD‐1, PD‐L1 and PD‐L2.This study involves both with genetic associations and protein expression of co‐stimulatory molecules (either stimulatory or inhibitory) in case‐control and population‐based studies. In the case‐control study, we categorized two types of model diseases: 1) the B‐cell induced autoantibody mediated disease, myasthenia gravis (MG) and 2) the T‐cell mediated inflammatory diseases, abdominal aortic aneurysm (AAA). In the population based study, we have selected subjects aged above 70 in the county of Uppsala, Sweden.At the genetic level, the key role of inhibitory receptors, B7H3 and Programmed Death‐1 (PD‐1), were evaluated in MG. No significant differences in genotype frequencies or allele frequencies in MG patients when compared with controls were found. The study, with PD‐ 1, was extended at mRNA and protein expression levels. Though we could not demonstrate any significant differences at mRNA levels, there was an increased expression of PD‐1 and PD‐L1 on T cells and monocytes, respectively. This demonstrates the existence regulatory mechanism behind MG.The soluble (s) forms of co‐stimulatory molecules sCD28, sCD80, sCD86, sCTLA‐4 were evaluated in patients with AAA and in general population. We could demonstrate increased circulating levels of soluble forms of CD28, CD86 and decreased levels of soluble forms of CTLA‐4 among AAA patients when compared with controls. In the general population, levels of soluble forms of co‐stimulatory molecules were positively related to pro‐inflammatory cytokines such as TNF‐α, IL‐6, IL‐1α, IL‐1β, IFN‐γ and chemokines such as IL‐8, but inversely related to CC chemokine, MCP‐1. We could not demonstrate any direct relation of soluble co‐stimulatory molecules to adhesion molecules and other atherosclerotic factors. The detection of soluble forms of PD‐1 could be demonstrated neither in the patients with MG nor in the controls.In conclusion, we suggest that the co‐stimulatory molecules have a significant impact on the status of the immune activation behind the two types of disorders. Therefore, we suggest that sCD28, sCD80, sCD86, sCTLA‐4 could be used as biomarkers for evaluating the process of inflammation. Furthermore, our study suggests a natural regulation of MG through the interaction between PD‐1/PD‐L1.List of scientific papersI. Sakthivel P, Wang X, Gharizadeh B, Giscombe R, Pirskanen R, Nyren P, Lefvert AK (2006). Single-nucleotide polymorphisms in the B7H3 gene are not associated with human autoimmune myasthenia gravis. J Genet. 85(3): 217-20. https://pubmed.ncbi.nlm.nih.gov/17406098 II. Sakthivel P, Shively V, Kakoulidou M, Pearce W, Lefvert AK (2007). The soluble forms of CD28, CD86 and CTLA-4 constitute possible immunological markers in patients with abdominal aortic aneurysm. J Intern Med. 261(4): 399-407. https://pubmed.ncbi.nlm.nih.gov/17391115 III. Sakthivel P, Wermeling F, Gu M, Hulthe J, Elmgren A, Kakoulidou M, Lefvert AK. Lind L (2007). Soluble CD28, CD80, CD86 and CTLA ]4 are related to CRP and proinflammatory cytokines and chemokines in elderly Caucasians. [Submitted]IV. Sakthivel P, Ramanujam R, Wang XB, Pirskanen Matell, Lefvert AK (2007). Programmed Death ]1: from gene to protein in autoimmune human myasthenia gravis. Journal of Neuroimmunology. [Accepted] https://pubmed.ncbi.nlm.nih.gov/18037500 </p
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