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Using crumb rubber particles obtained from end-of-life tires as aggregate in concrete can reduce the environmental overburden caused by the huge accumulation of these scrap tires. However, reduction in the mechanical properties of concrete is observed with the incorporation of rubber aggregates. To counter this detrimental effect of crumb rubber in concrete, amorphous metallic fibers are added to balance the loss in strength and durability issues. Mechanical characteristics along with the fracture energy of rubberized fiber-reinforced mortar are presented here. Four mortar mix compositions were investigated; the first one is reference mortar (control mortar), the second mix containing 30 kg/m3 of metallic fibers, the third mix containing 30% of rubber aggregates as replacement of sand by equivalent volume and fourth containing both rubber aggregates and metallic fibers with the dosage 30% and 30 kg/m3, respectively. Compression tests, modulus of elasticity and direct tension tests were conducted for mechanical characterization. Deformation capacity, residual post-cracking strength and fracture energy of these composite mortar mixes were evaluated through uniaxial direct tension tests. The fracture energy was determined from the obtained complete softening curves. Test results show a reduction in mechanical properties with the incorporation of crumb rubber as aggregates in mortar. However, a significant increase in fracture energy was observed in rubberized fiber-reinforced mortar mixes. Moreover, the mortar mixes containing both rubber aggregates and metallic fibers show positive synergetic effect resulting in enhanced post-cracking residual tensile strength, strain capacity and energy dissipation capacity. [ABSTRACT FROM AUTHOR]

Structural health monitoring of concrete infrastructure is a critical concern for timely repair and maintenance. This study provides an innovative approach utilizing smart concrete integrated with multi-walled carbon nanotubes (MWCNTs) to enhance electrical conductivity. The smart concrete's self-sensing capability is assessed through fractional change in electrical resistance (FCR) measured using a four-probe technique. Four-point bending and compressive tests explore the material's response to cyclic and monotonic loads. Additionally, the impact of saturation levels on self-sensing sensitivity is investigated through compressive tests on varying saturation degrees. Remarkably, a substantial correlation between crack mouth opening displacement (CMOD) and FCR is observed during cyclic bending tests, where FCR increases significantly (from 0.019% to 154%) as CMOD rises from 0.004 mm to 0.55 mm. Digital image correlation (DIC) further validates CMOD measurements and their correlation with FCR. Moreover, this study reveals that amplitude of loading and degree of saturation have a significant effect on the self-sensing of the smart concrete. In saturated conditions, the self-sensing response of the material is insensitive to the mechanical strain, while with reduction in the saturation degree, a quasi-linear response is observed. To assess the sensitivity of the smart concrete, stress and strain sensitivities were evaluated, revealing a noteworthy enhancement of approximately 33% and 50% in stress and strain sensitivity, respectively, as saturation levels decreased. The self-sensing response of the material is very sensitive to the mechanical strain during monotonic loading and damage. These findings indicate the potential of smart concrete as a promising tool for comprehensive, real-time structural health monitoring for infrastructure during its entire life. [ABSTRACT FROM AUTHOR]

Nowadays, the growing integration of renewable energy sources poses several challenges to electrical energy systems. The latter need be controlled by grid rules to ensure their stability and maintain the efficiency of renewable energy consumption. In this context, a novel HESS (hybrid energy storage system) control strategy, combining the PV (photovoltaic) generator with FLC (fuzzy logic control), SC (super-capacitor), and lithium-ion battery modules, is advanced. The proposed energy control rests on monitoring of the low-frequency and high-frequency electrical power components of the mismatch between power demand and generation, while applying the error component of the lithium-ion battery current. On accounting for the climatic condition and load variation considerations, the SC undertakes to momentarily absorb the high-frequency power component, while the low-frequency component is diverted to the lithium-ion battery. To improve the storage system's performance, lifetime, and avoid load total disconnection during sudden variations, we consider equipping the envisioned energy control design with controllers of SM and ANN types. The MATLAB/Simulink based simulation results turn out to testify well the investigated HESS control scheme's outstanding performance and efficiency in terms of DC bus voltage rapid regulation, thereby enhancing the battery's lifetime and ensuring the PV system's continuous flow. [ABSTRACT FROM AUTHOR]

In this study, the durability of cement-based repairs was observed, especially at the interface of debonding initiation and propagation between the substrate–overlay of thin-bonded cement-based material, using monotonic tests experimentally and numerically. Overlay or repair material (OM) is a cement-based mortar with the addition of metallic fibres (30 kg/m3) and rubber particles (30% as a replacement for sand), while the substrate is a plain mortar without any addition, known as control. Direct tension tests were conducted on OM in order to obtain the relationship between residual stress-crack openings (σ-w law). Similarly, tensile tests were conducted on the substrate–overlay interface to draw the relationship between residual stress and opening of the substrate–overlay interface. Three-point monotonic bending tests were performed on the composite beam of the substrate–overlay in order to observe the structural response of the repaired beam. The digital image correlation (DIC) method was utilized to examine the debonding propagation along the interface. Based on the different parameters obtained through the above-mentioned experiments, a three-point bending monotonic test was modelled through finite elements using a software package developed in France called CAST3M. Structural behaviour of repaired beams observed by experimental results and that analysed by numerical simulation are in coherence. It is concluded from the results that the hybrid use of fibres and rubber particles in repaired material provides a synergetic effect by improving its strain capacity, restricting crack openings by the transfer of stress from the crack. This enhances the durability of repair by controlling propagation of the interface debonding. [ABSTRACT FROM AUTHOR]

This paper presents a new control technique based on uncertain fuzzy models for handling uncertainties in nonlinear dynamic systems. This approach is applied for the stabilization of a multimachine power system subject to disturbances. In this case, a state-feedback controller based on parallel distributed compensation (PDC) is applied for the stabilization of the fuzzy system, where the design of control laws is based on the Lyapunov function method and the stability conditions are solved using a linear matrix inequalities (LMI)-based framework. Due to the high number of system nonlinearities, two steps are followed to reduce the number of fuzzy rules. Firstly, the power network is subdivided into sub-systems using Thevenin's theorem. Actually, each sub-system corresponds to a generator which is in series with the Thevenin equivalent as seen from this generator. This means that the number of sub-systems is equal to the number of system generators. Secondly, the significances of the nonlinearities of the sub-systems are ranked based on their limits and range of variation. Then, nonlinearities with non-significant variations are assumed to be uncertainties. The proposed strategy is tested on the Western systems coordinating council (WSCC) integrated with a wind turbine. The disturbances are assumed to be sudden variations in wind power output. The effectiveness of the suggested fuzzy controller is compared with conventional regulators, such as an automatic voltage regulator (AVR) and power system stabilizers (PSS). [ABSTRACT FROM AUTHOR]

The purpose of this paper is to establish the cyclic bridging law of fibre-reinforced and rubberised materials. In this regard, uniaxial tensile fatigue tests controlled by crack mouth opening displacement were conducted. Different mortars incorporating or not rubber aggregates were tested and compared. Results show that the bridging stress decreases with the number of fatigue cycles for the same maximum crack width, irrespective of nature of the composite. The cyclic bridging stress degradation for large pre-cracked widths is limited for mortar reinforced with metallic fibres. In case of rubberised mortar, cyclic bridging stress degradation is limited at small pre-cracked width values. A combined use of rubber aggregates and fibres in the mortar appeared to be a suitable solution to limit the cyclic bridging stress degradation. Moreover, a mathematical fit on cyclic crack bridging law for fibre-reinforced and rubberised materials is proposed. [ABSTRACT FROM AUTHOR]

This study focuses on different techniques for dispersing Multi-Walled Carbon Nanotubes (MWCNTs) in cementitious materials. The impact of dispersion is observed through electrical resistivity and mechanical properties of cementitious composites. Two contents (0.5 and 1% by mass of cement) of MWCNTs are investigated and three different techniques were used to disperse CNTs in water by sonication: (i) pristine, P-CNT, (ii) functionalized carbon nanotubes by classical approach (dispersive agent, D-CNT), and (iii) by an innovative approach (annealing, A-CNT). Self-sensing response of the material under cyclic compressive loading is measured with Wheatstone Bridge (WSB) circuit. Results showed a detrimental effect of dispersive agent on the resistivity and mechanical properties of cementitious composites irrespective of the content of CNTs. However, the impact of P-CNT and A-CNT on the reduction of mechanical properties is slight. With the use of 1% content of A-CNTs, a stable resistivity response of the material is observed irrespective of the saturation degree. This indicates that content higher than 1% of A-CNTs is not required for the development of smart cementitious composites for structural health monitoring (SHM). The test results of self sensing measurements indicate a poor repeatability of the electrical response for plain mortar under each loading cycle while, stable response is noticed with specimens incorporating 1% of A-CNTs. The maximum variation in fractional change in voltage (FCV) shown by plain mortar is 6.3% indicating high electrical resistance of plain mortar, while in case of mortar containing 1% A-CNTs, variation in FCV is 35% indicating lower electrical resistance and better sensitivity of the material. [ABSTRACT FROM AUTHOR]

The paper focuses on the debonding between a cement-based overlay and a concrete substrate under a mechanical loading. Two categories of substrate surface preparation were considered: Sawing the Substrate and Sand Blasting of the casting surface of the substrate. Untreated substrate surface used in its original state was taken as the Reference Surface. The overlay material investigated was a cement-based mortar. Direct tensile tests perpendicular to the overlay-substrate interface were carried out at the age of 28 days and the results (tensile strength, residual post peak behavior) are presented and discussed. Attention was paid to the Sand Blasted surface which is a more realistic model of practical field conditions. The debonding propagation under monotonic and fatigue loading was monitored for sand blasted surfaces using the Digital Image Correlation technique. Results indicate that both surface preparation technique has its own efficiency level and gives different roughness. Among the techniques used, greater bond strength improvement was observed with the sawn substrate surface than with the sandblasted one. Moreover, under cyclic loading, major debonding along the interface occurs from the first cycle to the 20000th cycle and is negligible thereafter. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of state estimation and sensor fault reconstruction conjointly for a class of nonlinear systems with time-varying uncertainties for which the nonlinear characteristic satisfies the Lipschitz circumstance. A hybrid approach based on an integral observer and sliding-mode theory has been proposed in order to model sensor fault as a virtual actuator one. For the augmented model, the observer matching condition is not satisfied. To overcome this problem, a new method, which improves the design approach and enhances the rapidity of the fault estimation convergence, has been proposed. The fault estimation error effect is minimized by integrating the H ∞ disturbance attenuation level. The proposed design is formulated and derived as a linear matrix inequality problem. Parameters of this observer are calculated through the linear matrix inequality technique. The proposed method has been validated through an example of a single-link manipulator robot. Simulation results show that this approach can estimate the state and the sensor fault successfully, despite the time-varying uncertainties and the presence of unknown inputs. [ABSTRACT FROM AUTHOR]

This paper presents a robust fault diagnosis scheme for a class of uncertain nonlinear systems whose nonlinear function satisfies the Lipschitz condition with unmatched time-varying uncertainties, external disturbances and perturbed output. The design procedure combines the high robustness of the nonlinear unknown input observer with sliding-mode techniques in order to enhance the estimation qualities. The proposed design is derived and expressed as a linear matrix inequality optimization problem. Additionally, we have provided an approach to reduce conservatism in the derivation of the stability conditions. The effectiveness of this observer and the fault diagnosis scheme are shown by applying them to a single-link manipulator. Simulation results are presented to validate the proposed approach and show the robustness for the system nonlinearity and unmatched time-varying uncertainties. [ABSTRACT FROM AUTHOR]

The paper deals with the control of complex dynamic systems. The main objective is to partition the whole operational system domain in local regions using an incremental neuro-fuzzy classifier in order to achieve multiple neural control strategies for the considered system. In our case, this approach is applied to a greenhouse operating during one day. Therefore, banks of neural controllers and direct neural local models are made from different partitioned greenhouse behaviors and two multiple neural control strategies are proposed to control the greenhouse. The selection of the suitable controller is accomplished by computing the minimal output error between desired and direct neural local models outputs in the case of the first control strategy and from a supervisor block containing the considered neuro-fuzzy classifier in the case of the second control strategy. Simulation results are then carried out to show the efficiency of the two control strategies. [ABSTRACT FROM AUTHOR]

In this paper, we propose an adaptive fuzzy controller for a class of nonlinear SISO time-delay systems. The plant model structure is represented by a Takagi-Sugeno (T-S) type fuzzy system. The T-S fuzzy model parameters are adjusted online. The proposed algorithm utilizes the sliding surface to adjust online the parameters of T-S fuzzy model. The controller is based on adjustable T-S fuzzy parameters model and sliding mode theory. The stability analysis of the closed-loop system is based on the Lyapunov approach. The plant state follows asymptotically any bounded reference signal. Two examples have been used to check performances of the proposed fuzzy adaptive control scheme. [ABSTRACT FROM AUTHOR]

The problem of sliding-mode control (SMC) with dissipativity for a class of time-delay Takagi-Sugeno fuzzy singular systems is investigated. The system is subject to uncertainties and input non-linearity. Based on an integral sliding surface, a delay-dependent criterion is developed in terms of linear matrix inequalities, which ensures the sliding mode dynamics to be robustly admissible and strictly (Q, S,R)-dissipative. Moreover, an SMC law is established such that the reachability of the specified sliding surface is guaranteed. Finally, the validity and applicability of the proposed approach are illuminated by two simulation examples. [ABSTRACT FROM AUTHOR]

The problem of observer-based robust control design is studied for discrete-time singular systems with norm-bounded uncertainties and a time-varying delay. More precisely, a delay-dependent criterion is established that guarantees the admissibility of the considered systems, without resorting to its decomposition. Based on the proposed criterion and without the assumption that the considered systems are admissible, robust observer-based controllers are designed for discrete-time singular time-delay systems such that the closed-loop systems have the characteristics of regularity, causality and asymptotic stability. Seeking computational convenience, all the developed results are cast in the format of strict linear matrix inequalities (LMIs). Finally, some numerical examples are presented to show the feasibility of the proposed approach. [ABSTRACT FROM AUTHOR]

This paper deals with the Maximum Power Point Tracking (MPPT) for photovoltaic energy system. It includes photovoltaic array panel, DC/DC converter, and load. The operating point for photovoltaic energy system depends on climatic parameters and load. For each temperature and irradiation pair, there exists only one optimal operating point which corresponds to the maximum power transmitted to the load. The photovoltaic energy system is described by nonlinear equations. It is transformed into an augmented system which is described with a Takagi-Sugeno (T-S) fuzzy model. The proposed MPPT algorithm which permits transfering the maximum power from the panel to the load is based on Parallel Distributed Compensation method (PDC). The control parameters have been computed based on Linear Matrix Inequalities tools (LMI). The Lyapunov approach has been used to prove the stability of the system. Some reliable simulation results are provided to check the efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of multi-objective control for a class of uncertain discrete-time fuzzy systems. The state-space Takagi-Sugeno T-S fuzzy model with linear fractional parameter uncertainties is adopted. Based on a linear matrix inequality approach and via so-called dynamic parallel distributed compensation, a fuzzy full-order dynamic output feedback controller is developed such that the L gain performance from the exogenous input signals to the controlled output is less than or equal to some prescribed value and, for all admissible uncertainties, the closed-loop poles of each local system are within a pre-specified sub-region of complex plane. Two numerical examples are provided to illustrate the effectiveness of the proposed design method. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, the problem of delay-dependent robust L2 − L ∞ (energy to peak) control for a class of uncertain fuzzy descriptor systems with time-varying delay is investigated. The parametric uncertainties are assumed to be of a linear fractional form involving all system matrices. First, a delay-dependent criterion is given in terms of LMIs to guarantee that the fuzzy descriptor system is regular, impulse free, and stable. Based on this criterion, a state fuzzy feedback controller is designed to ensure that the closed-loop system is regular, impulse free, and robustly stable with a prescribed L2 − L ∞ performance satisfied for all admissible parameter uncertainties. Numerical examples are given to show the effectiveness of the proposed approach. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, Multivariable Generalized Predictive Control (MGPC) is presented. If a physically realizable multivariable process can be described by a Controlled Auto-Regressive Integrated Moving Average (CARIMA) model with non identity disturbance polynomial matrix : C(q-1)≠ Im, the way to get MGPC controller coefficients can be simplified. Since, there exist direct expressions describing the relationship between the open-loop model parameters and the MGPC controller coefficients according to a certain set of tuning parameters. The control moves are just the product of the process known information and the MGPC controller coefficients. This technique is based on the Generalized Predictive Control (GPC) approach. The adopted strategy consists, first of all, in the formulation of the output's predictor of the model. Secondly, the elaboration of the control law for the linear system is then envisaged. This stage is conceived by means of the transformation of the quadratic criterion to minimize. Lastly, the main characteristic of the algorithm is to take into account the coloring polynomials of the noise. The proposed control algorithm is evaluated on experiment results. [ABSTRACT FROM AUTHOR]

In this article, a new approach regarding H ∞ and non-fragile stability analysis and observer-based controller synthesis problem for a class of discrete-time fuzzy systems is investigated. The multiplicative gain variations under consideration are contained in both the controller gain and observer gain. By defining a basis-dependent Lyapunov function and introducing some additional matrix variables, new sufficient conditions are derived to guarantee the stability of the non-fragile H ∞ observer-based control system. Seeking computational convenience, the developed results are cast in the format of linear matrix inequalities and two numerical examples are presented to illustrate the feasibility of theoretical developments. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the delay-dependent robust reliable guaranteed cost (RRGC) fuzzy control problem for discrete-time nonlinear systems with time-varying delays. The delays may simultaneously appear in the state and in the control input. Also, both parametric uncertainties and control component failure may exist. Through Takagi-Sugeno fuzzy modelling of nonlinear delayed-systems and based on an appropriate piecewise Lyapunov-Krasovskii functional, a piecewise fuzzy controller is designed. Sufficient conditions for the existence of a RRGC controller are derived in terms of linear matrix inequalities (LMIs). Furthermore, a suboptimal RRGC fuzzy controller is given by means of a convex optimization procedure with LMI constraints which can not only guarantee the stability of the closed-loop fuzzy system, but also provides an optimized upper bound of the given cost performance despite possible actuator faults. Two numerical examples are presented in this paper to illustrate the feasibility of the theoretical developments. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of non-fragile (resilient) H∞ control for a class of state-delay nonlinear discrete-time systems described by (TS) fuzzy models where both the state feedback and static output feedback are investigated. Based on basis-dependent Lyapunov-krasovskii function, sufficient conditions are derived to achieve the system stability and the H∞ performance. The linear matrix inequality (LMI) approach is proposed to obtain the state-feedback gains, and a homotopy-based iterative LMI algorithm is developed to get the static output feedback gains. An illustrative example shows the effectiveness and the feasibility of the theoretical developments. [ABSTRACT FROM AUTHOR]

In this paper we are interested in robust adaptive fuzzy control of nonlinear SISO systems in the presence of parametric uncertainties. The plant model structure is represented by the Takagi-Sugeno (T-S) type fuzzy system. An indirect adaptive fuzzy controller based on model reference control scheme is proposed to provide asymptotic tracking of reference signal. The controller parameters are computed at each time. The plant state tracks asymptotically the state of the reference model for any bounded reference input signal. Inverted pendulum and mass spring damper are used to check the performance of the proposed controller. [ABSTRACT FROM AUTHOR]

Focuses on the extension of the circle diagram to the doubly fed synchronous machine (DFSM). Generalization of the torque line under doubly fed conditions; Implementation of numerical control techniques; Determination of the machine steady-state characteristics.

In this work, we present a physics‐based model for a two‐dimensional electron gas (2‐DEG) density at heterointerface in AlGaN/GaN high electron mobility transistor (HEMT). One‐dimensional Schrödinger‐Poisson equations are solved self‐consistently using a nonuniform mesh within the framework of the nextnano device simulation software. The 2‐DEG density of AlGaN/GaN HEMT is investigated through the dependence of electron concentrations on various structural parameters such as barrier layer thickness, doping concentration, and the Al content. We report calculations of gate capacitance from charge density characteristics with respect to gate voltage. Good agreement between calculation and experiment is found. [ABSTRACT FROM AUTHOR]

New compounds (IIIb)-(IIIe) possess antifungal activities against B. [ABSTRACT FROM AUTHOR]

• Rubberized cement-based composites are suitable materials for pavements. • The composites have higher strain capacity and low propensity for cracking. • Rubberized roller/self-compacted concretes were used for pavements. • Field applications confirmed the applicability of the composites in pavements. • Future considerations for rubberized cement-based pavements were discussed. Properties of rubberized cement-based composites have been investigated and the up-to-date research findings have demonstrated the practical feasibility of using the materials for large surface applications. Despite the detrimental effect in some mechanical properties, beneficial characteristics known as improved strain capacity, low propensity for restrained shrinkage cracking, high freeze-thaw resistance, better sound insulation, etc. make such composites relatively interesting for pavements such as road dedicated for low traffic volume, base or sub-base courses, or overlays. This review paper focuses on advantageous properties of rubberized cement-based materials and potential for pavement applications including rigid pavements, semi-flexible pavements, block pavers, cement-treated bases/sub-bases, and thin bonded overlays. General conclusions and further possible considerations to popularize the use of rubber aggregates in pavements as one of the most relevant solutions to recycle end-of-life rubber tires are also presented. [ABSTRACT FROM AUTHOR]