Sharma, Atul Kumar

Dielectric elastomers (DEs) have significant potential in many applications, particularly in the realm of soft robotics, owing to their capability of undergoing large deformation. The viscoelastic creep response exhibited by dielectric elastomers when subjected to electrostatic input is an inherent characteristic of DEs that hinders their long-term performance and applicability. This behavior leads to time-dependent deformation during actuation, which limits their use as actuators in applications such as robotic grasping. This work presents control techniques that have been developed to minimize viscoelastic creep in dielectric elastomer actuators (DEAs). To simulate the viscoelastic creep behavior of DEAs under dynamic loading, a dynamic modeling framework is presented. The equations derived from the dynamic model are subsequently subjected to the two different control strategies using Linear Quadratic Regulator and Model Predictive Control. Control strategies have been devised to minimize creep and decrease the reaction time. The key aspect of both methods involve the development of an objective function, which is then optimized to determine the ideal control input voltage. The suggested control methods involve applying the fundamental optimal control concepts to an actuator. The actuator response on the application of a single-step input is observed. This principle is then extended to include the actuator response which is a multi-step signal using the proposed control strategy. The results suggest that the control methods are capable of efficiently dealing with the viscoelastic properties of the actuator to achieve different desired equilibrium conditions and hence optimize the performance of the actuator. The simulation results demonstrate that both the control strategies reduce the response time of the DEA by about 98% and also improve the steady-state response. This paper’s findings have the potential to be applied to the development of a control system for the mitigation of viscoelastic creep in DEAs.

We demonstrate the possibility of controlling the success probability of a secret sharing protocol using a quantum cloning circuit. The cloning circuit is used to clone the qubits containing the encoded information and en route to the intended recipients. The success probability of the protocol depends on the cloning parameters used to clone the qubits. We also establish a relation between the concurrence of initially prepared state, entanglement of the mixed state received by the receivers after cloning scheme and the cloning parameters of cloning machine. © 2014 Springer Science+Business Media New York.

This work presents a finite element framework for simulating the quasi-static response of dielectric elastomer-based minimum energy structure (DEMES). The DEMES is an actuator formed by combining an inextensible frame and pre-stretched dielectric membrane that exhibits the unique shape-morphing characteristics of the actuator. A continuum strain energy-based model is implemented to investigate the impact of the different geometrical parameters on the performance of the DEMES actuator. Finite element analyses are performed using user-defined element (UEL) in ABAQUS for determining the equilibrium shape of the actuators and further investigating their electromechanical response. Experiments are performed using the commercially available VHB-4910 acrylic tape and the PET frames. 3D-printed reinforcements are used to impart anisotropy in the specimen. The findings of the model solutions provide preliminary insights on the alteration of the initial and final configurations of the DEMES affected by different geometrical parameters. It is observed that the shape of the electrode (rectangular, circular and triangular), compliant frame (rectangular, circular and triangular) and implemented stiffeners appreciably alter the attained initial configuration, final configuration and actuation range of the DEMES actuator. In general, this investigation can find its potential use in designing the futuristic DEMES through topological optimization of the compliant electrode and frame geometry together with material anisotropy of the elastomer.

Soft dielectric elastomers (SDEs) represent a category of intelligent electroactive materials utilized in electro-mechanical actuation technology. The dynamic performance of these materials during actuation is notably affected by intrinsic factors like crosslinks, entanglements and the limited extensibility of polymer chains. In this paper, we provide a theoretical framework for modeling the dynamic behavior of a balloon actuator made up of soft dielectric elastomer. To account for the inherent characteristics of polymer chain networks, we employ a physics-based nonaffine material model proposed by Davidson and Goulbourne. The governing equation for dynamic motion is established using Euler–Lagrange’s equation of motion for conservative systems. The reported dynamic modeling framework is then utilized to explore the transient response, stability, periodicity and resonance properties of a dielectric elastomer balloon (DEB) actuator for varying levels of polymer chain crosslinks, entanglements and finite extensibility parameters. To assess the periodicity and stability of the nonlinear vibrations exhibited by the DEB actuator, we present Poincaré maps and phase-plane plots. The results demonstrate that changes in the density of polymer chain entanglements lead to transitions between quasi-periodic and aperiodic vibrations. These findings represent an essential initial step toward the design and production of intelligent soft actuators with diverse applications in future technologies.

Hard-magnetic soft materials (HMSMs) are a class of magnetoactive smart polymers capable of sustaining a high residual magnetic flux density and can undergo large actuation strains under an external magnetic excitation. Due to these exceptional characteristics, soft actuators based on HMSMs hold enormous potential for remote-controlled applications. The temperature and viscoelasticity considerably influence the performance of these materials during the operation. This work aims to develop an analytical framework for modeling the dynamic behavior of a planar hard-magnetic soft actuators (HMSA) considering temperature and viscoelastic effects. The constitutive behavior of the viscoelastic HMSA is described by employing an incompressible neo-Hookean model in conjunction with a Zener rheological model and the Rayleigh dissipation function. The dynamic governing differential equations of motion are derived by utilizing the non-conservative form of the Euler–Lagrange equation. This study delves into the collective influence of temperature and viscoelastic properties on the stability, periodicity, and resonance characteristics of nonlinear vibrations exhibited by HMSM-based planar actuator subjected to dynamic magnetic loading, presenting the findings through time-history responses, Poincaré maps, and phase-plane plots. The presented results can help in the efficient and robust design of HMSM-based actuators and can also serve as an initial step toward the development of advanced actuators exposed to dynamic loading under variable temperatures for diverse applications in the fields of engineering and medicine.

This article comprehensively explores matrices and their prerequisites for achieving positive semi-definiteness. The study delves into a theorem concerning pure quantum states in the context of weighted graphs. The main objective of this study is to establish a graph-theoretic framework for the study of quantum discord and to identify the necessary and sufficient conditions for zero quantum discord states using combination of local unitary operators. This research aims to advance the understanding of quantum discord and its implications for quantum information theory with a graph-theoretic framework. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.

Minimum energy structures made up of smart electro-active polymers (SEAPs) have attracted significant attention in the field of soft robotics and actuators due to their exceptional property of undergoing large deformations when subjected to electric fields. In general, temperature also plays a crucial role in modeling of SEAPs because it affects the mechanical, electrical, and thermal properties of the polymer. These properties, in turn, determine the performance of smart polymer-based devices. Motivated by these ongoing advancements, this study investigates the effects of temperature on the nonlinear dynamic behavior of a smart dielectric elastomer-based minimum energy structure (SDEMES) actuator. The governing dynamic equation of the actuator is derived using the standard Euler–Lagrange's equation. Through the utilization of time-evolution diagrams, Poincaré plots, and phase portraits, the study comprehensively evaluates the effects of temperature on the stability, periodicity, and resonant behavior of the actuator. The results highlight the significant influence of temperature on the stiffness of the elastomer within the SDEMES actuator, directly impacting its actuation performance. The frequency response of the actuator demonstrates a distinct increase in resonant frequency as the temperature rises. These findings shed light on the crucial role of temperature in shaping the stiffness and nonlinear dynamic behavior of smart dielectric elastomer minimum energy structures.

In this paper, we present a theoretical model for the analysis of large magneto-deformation and the anti-plane shear wave bandgaps in 2D periodic two-phase hard magnetic soft composite structures subjected to magnetic stimuli. The constitutive behavior of the phases in the hard-magnetic soft composite is described using the incompressible Gent model. To solve the incremental anti-plane wave equations, the finite element method and the Floquet–Bloch theorem for periodic media are utilized. Using the developed framework, we numerically study the dependency of the bandgap width and their location on the direction and magnitude of the applied magnetic flux density vector, material parameter contrasts, and geometry and volume fraction of the inclusion phase. The numerical results reveal that significant tunability of the bandgap is achieved when the applied magnetic flux density direction is along the residual magnetic flux density direction. Also, it is seen that the geometry of the inclusion has significant effect on the bandgap width. The crucial inferences from the present investigation can find their potential use in the design and manufacturing of futuristic smart soft wave devices with tunable band structures.

The polymer chain network within the dielectric elastomers (DEs) contains numerous entanglements, crosslinks and finite extensibility, all of which play a substantial role in the nonlinear finite deformation behavior of the DE-based phononic crystals. In this study, a theoretical model is proposed to investigate the intricate interplay between internal polymer chain entanglements, crosslinks and finite extensibility, and their influence on the tunable band gap properties of soft dielectric elastomer phononic crystals. To capture the inherent characteristics of the polymer chain network, a physics-based nonaffine material model is employed. By incorporating nonlinear electro-elasticity theory and the linearized incremental theory, the equations governing the voltage-induced finite deformation and superimposed incremental anti-plane shear waves are formulated. Employing the finite element method and Bloch's theorem, the band structure of an infinite periodic DE phononic crystal is extracted. The numerical results reveal that under higher electric fields, the intrinsic properties of the polymer network significantly impact the band gap characteristics of DE phononic crystals. The outcomes of the numerical simulations and the insights derived from this study offer valuable guidance for the design and manufacturing of soft electro-statically tunable phononic structures.

In this manuscript, universal quantum teleportation in the presence of memory or memory-less dynamics with applications of partial collapse measurement operators is analyzed. These results show that the combined effects of memory or non-Markovianity, and weak measurements can lead to universal quantum teleportation (UQT). This study involves noise models of physical importance having characteristic Markovian and non-Markovian regions, allowing one to observe a transition in quantum properties as one switches from non-Markovian to Markovian dynamics. For this, the effects of different types of non-Markovianity are characterized for efficient UQT, both due to the retention of correlations for a longer duration and due to information backflow. The memory effects arising from a correlated channel with or without weak measurements are analyzed further. Interestingly, this analysis for a correlated amplitude damping channel shows that memory effects are of significant advantage in minimizing the fidelity deviation. The presence of weak measurements further enhances the realization of UQT in the presence of memory. The ability of memory effects to achieve zero fidelity deviation at non-zero time is interesting and of experimental importance.