Transient Response Behavior Research Articles

Multi-objective resistance-capacitance optimization algorithm: An effective multi-objective algorithm for engineering design problems

Focusing on practical engineering applications, this study introduces the Multi-Objective Resistance-Capacitance Optimization Algorithm (MORCOA), a new approach for multi-objective optimization problems. MORCOA uses the transient response behaviour of resistance-capacitance circuits to navigate complex optimization landscapes and identify global optima when faced with many competing objectives. The core approach of MORCOA combines a dynamic elimination-based crowding distance mechanism with non-dominated sorting to generate an ideal and evenly distributed Pareto front. The algorithm's effectiveness is evaluated through a structured, three-phase analysis. Initially, MORCOA is applied to five benchmark problems from the ZDT test suite, with performance assessed using various metrics and compared against state-of-the-art multi-objective optimization techniques. The study then expands to include seven problems from the DTLZ benchmark collection, further validating MORCOA's effectiveness. The final phase involves applying MORCOA to six real-world constrained engineering design problems. Notably, the optimization of a honeycomb heat sink, which is crucial in thermal management systems, is a significant part of this study. This phase uses a range of performance measures to assess MORCOA's practical application and efficiency in engineering design. The results highlight MORCOA's robustness and efficiency in both real-world engineering applications and benchmark problems, demonstrating its superior capabilities compared to existing algorithms. The effective use of MORCOA in real-world engineering design problems indicates its potential as an adaptable and powerful tool for complex multi-objective optimization tasks.

Active vibration control of rotating smart bidirectional FGPTC subjected to internal mechanical shock

This study considers the active vibration control of a sandwich truncated cone, whose intermediate layer is made of bidirectional functionally graded (FG) porous material bonded with integrated piezoelectric actuator and sensor layers on its outer and inner surfaces. The material properties of the bidirectional functionally graded porous truncated cone (FGPTC), with even and uneven porosity distributions along the length and thickness directions, are changed using a power law function. The governing motion equations utilize the two-dimensional (2D) axisymmetric theory of elasticity rather than simple shell theories. The solving of the governing motion equations is accomplished through the utilization of graded finite element and Newmark methods. The study investigates the impact of dimensions, parameters, and porosity types on transient response behavior, including the semi-vertex angle and the ratio of truncated cone length to outer radius. Furthermore, the effects of power index, porosity volume fractions, rotational velocities, and boundary conditions are examined. Active vibration control (AVC) of the piezoelectric FGPTC is achieved by employing a closed-loop control algorithm based on velocity feedback. Several numerical simulations are conducted to evaluate the effectiveness of the proposed active vibration control system in reducing structural vibrations. The results demonstrate significant reductions in vibration amplitudes and improved structural stability achieved through the active control approach.

Optimal Excitation and Readout of Resonators Used as Wireless Passive Sensors.

Resonators are passive time-invariant components that do not produce a frequency shift. However, they respond to an excitation signal close to resonance with an oscillation at their natural frequencies with exponentially decreasing amplitudes. If resonators are connected to antennas, they form purely passive sensors that can be read remotely. In this work, we model the external excitation of a resonator with different excitation signals and its subsequent decay characteristics analytically as well as numerically. The analytical modeling explains the properties of the resonator during transient response and decay behavior. The analytical modeling clarifies how natural oscillations are generated in a linear time-invariant system, even if their spectrum was not included in the stimulation spectrum. In addition, it enables the readout signals to be optimized in terms of duration and bandwidth.

Transient Dynamic Response and Delay Behavior of Tire on M-Step Road

Transient Dynamic Response and Delay Behavior of Tire on M-Step Road

Improving the transient thermal response and ablation properties of epoxy‐modified silicone rubber composites by adding fluxing agent

AbstractIn this work, transient thermal response and ablation behavior of liquid silicone rubber composites containing fluxing/ceramic forming fillers were investigated under different heat flows using an oxyacetylene flame. The results indicated that the introduction of zinc borate (ZB) and aluminum oxide (Al2O3) effectively reduced the temperature at various depths of the samples, and they improved the thermal insulation properties and lowered pyrolysis rates. The above finding was attributed to the heat absorption arising from water release and melt filling as well as the vitrified reaction of solid melt due to the decomposition of ZB. Besides, the melting and exfoliation of Al2O3 and the formation of aluminum silicate (Al2SiO5) caused heat absorption effect. Additionally, the mass ablation rates and line ablation rates increased with rising heat flows coupling with a decrease of compressive strength of the char layers. In a nutshell, the effect of adding ZB/Al2O3 on the thermal insulation behavior of epoxy‐modified vinyl silicone rubber (EMVSR) composites under different heat flows was elucidtaed. This work served as a reference for the design and preparation of flexible ablative materials for thermal protection applications.

Transient Response and Firing Behaviors of Memristive Neuron Circuit.

The signal transmission mechanism of the Resistor-Capacitor (RC) circuit is similar to the intracellular and extracellular signal propagating mechanism of the neuron. Thus, the RC circuit can be utilized as the circuit model of the neuron cell membrane. However, resistors are electronic components with the fixed-resistance and have no memory properties. A memristor is a promising neuro-morphological electronic device with nonvolatile, switching, and nonlinear characteristics. First of all, we consider replacing the resistor in the RC neuron circuit with a memristor, which is named the Memristor-Capacitor (MC) circuit, then the MC neuron model is constructed. We compare the charging and discharging processes between the RC and MC neuron circuits. Secondly, two models are compared under the different external stimuli. Finally, the synchronous and asynchronous activities of the RC and MC neuron circuits are performed. Extensive experimental results suggest that the charging and discharging speed of the MC neuron circuit is faster than that of the RC neuron circuit. Given sufficient time and proper external stimuli, the RC and MC neuron circuits can produce the action potentials. The synchronous and asynchronous phenomena in the two neuron circuits reproduce nonlinear dynamic behaviors of the biological neurons.

Enhanced dynamic performance in DC–DC converter‐PMDC motor combination through an intelligent non‐linear adaptive control scheme

A novel neuro-adaptive control scheme is proposed in the context of angular velocity tracking in DC–DC buck converter driven permanent magnet DC motor system. The controller builds upon the idea of backstepping and consists of a fast single hidden layer Hermite neural network (HNN) module equipped with on-board (adaptive) learning to counteract the unknown non-linear time-varying load torque and to ensure nominal tracking performance. The HNN has a simple structure and exhibits promising speed and accuracy in estimating dynamic variations in the unknown load torque apart from being computationally efficient. The proposed method guarantees a rapid recovery of nominal angular velocity tracking under parametric and non-parametric uncertainties. In order to verify the performance of the proposed neuro-adaptive speed controller, extensive experimentation has been conducted in the laboratory under various real-time scenarios. Results are obtained for start-up, time-varying angular velocity tracking and under the influence of highly non-linear unknown load torque. The performance metrics such as peak undershoot/overshoot and settling time are computed to quantify the transient response behaviour. The results clearly substantiate theoretical propositions and demonstrate an enhanced dynamic speed tracking under a wide operating regime, thus confirming the suitability of proposed method for fast industrial applications.

The Design of DDS ADPLL using ARM Micro Controller

Abstract: Abstract In this article, a full custom design and implementation of a sine wave All Digital Phase Lock Loop (ADPLL) system based on ARM microcontroller is described. These ADPLL implementations are also referred as Software - Direct Digital Synthesis ADPLL (DDS-ADPLL). In the literature, the work related to software DDS ADPLLs is to achieve a specific transient response or dynamic behavior. However, there are few literature that addresses the issues encountered while implementing the Sine wave ADPLL on hardware. This work identifies the problem one may face while implementing the DDS-ADPLLs on microcontroller and proposes methods / solutions to mitigate those issues. Moreover, in order to minimize jitter it is proposed to use timer interrupts and integer datatype. The design procedure of this work uses only integer datatype forimplementation. Keywords: DDS ADPLL; ADPLLs; All Digital PLL; Phase Locked Loop; LPC2148ADPLL

Design Framework and Laboratory Experiments for Helix and Slinky Type Ground Source Heat Exchangers for Retrofitting Projects

The focus of the experimental work was on shallow spiral geothermal heat exchanger configurations. Real-scale experiments were carried out for vertically oriented spiral collectors (helix) in sand and soil. One objective was to develop a measurement concept in laboratory environment to create a framework for a validated database. This database serves as the basis for further and new development of engineering design tools. To achieve the highest possible data-point density in the observed environment, temperature sensors and a fiber-optic temperature measurement system (DTS) were used. Soil probes were taken in situ before and after the measurements and analyzed at a thermophysical laboratory to determine material properties. The heat flow was controlled by an electric heating cable, which was installed in the form of a spiral-shaped heat exchanger in a 1 m³ container. To guarantee constant boundary conditions, the measurements were carried out in a climate chamber at a defined ambient temperature. The evaluation of the transient response behavior is spatially resolved. The results are coordinate-based temperature points, which describe temperature gradients in all axes of the container over time, which are combined with known soil properties. The collected data was used to develop computational fluid dynamic (CFD) models, which are used to extend the variety of geometry and soil configurations for developing new design tools.

Correlation between Transient Response and Neuromorphic Behavior in Organic Electrochemical Transistors (Adv. Electron. Mater. 4/2022)

Organic Neuromorphic Devices The working mechanism of neuromorphic devices on organic electrochemical transistors is investigated in article 2101186 by Shunsuke Yamamoto and co-workers. The experimental and modeling results highlight the importance of the ionic movements in the device. These insights pave the way for a rational design of OECT-based neuromorphic devices.

Observer‐based adaptive controller design for chaos synchronization using Bernstein‐type operators

AbstractThis article uses the Bernstein‐type operators as the universal approximator to present an observer‐based robust adaptive controller for chaos synchronization. The lumped uncertainties including, un‐modeled dynamics and external disturbances, are modeled with this potent mathematic tool. It is shown that using the Bernstein‐type operators as basis functions and tuning the polynomial coefficients by the adaptive laws calculated in the stability analysis, uniform ultimate boundedness of the observer estimation error and synchronization error can be assured. To analyze the performance of the proposed controller scheme in terms of transient response behavior and robustness, the Duffing–Holmes oscillator is considered as the simulation testbed. A set of two different experiments are conducted to evaluate the efficiency of the introduced control approach. The performance of the proposed approach is also compared with RBFNN as a powerful approximation method. Unlike neural network/fuzzy methods, which require system states as inputs to estimate functions and construct a regressor vector, the proposed method is not dependent on the system states. Furthermore, there are more adjustable parameters in the regressor vector of the RBFNN (such as the width and center of the Gaussian units), and assigning the best values for these parameters is tedious and time‐consuming work due to the repeated trial and error.

Correlation between Transient Response and Neuromorphic Behavior in Organic Electrochemical Transistors

AbstractThe factors controlling the neuromorphic response of organic electrochemical transistors (OECTs) are examined. In these devices, the gate voltage is used to supply the pre‐synaptic input, while the drain current is taken as the post‐synaptic output. The behavior of devices made from polymer blends of a mixed conductor (PEDOT:PSS) and an ion conductor (PSSNa) is analyzed. The experimental results highlight that the post‐synaptic response timescale depends on the size of ion in the electrolyte. Modeling shows that the neuromorphic response is controlled by the transient response of the ionic circuit of the OECT. These insights on device response time pave the way for a more rational design of OECT‐based neuromorphic devices.

Chaos synchronization using differential equations as extended state observer

In this paper, an extended state observer (ESO) is presented for synchronizing a chaotic master-slave system based on linear differential equations. The universal approximation property enables linear differential equations to estimate uncertainties, consisting of disturbances and unmodeled dynamics. The main contribution of this study is developing a control scheme based on ESO, which is designed using differential equations. In other words, an Nth-order linear differential equation is utilized to model the lumped uncertainty. The controller is proposed based on a model-free approach to eliminate the need for accurate information from the system model and assure a robust tracking performance. Furthermore, a thorough mathematical analysis is given based on the Lyapunov stability theorem to confirm the uniform ultimate boundedness of the observation/tracking approximation errors. To analyze the performance of the ESO-controller scheme in terms of transient response behavior and robustness, the Duffing-Holmes oscillator is considered as the simulation testbed. A set of five different experiments are conducted to evaluate the efficiency of the introduced control approach. The results of ESO are also compared with two powerful approximation methods.

Evaluating Coordinated Cooperative Control of Three Active Car Systems Using Fuzzy-Logic

Vehicle systems automation is an inevitable process as a result of the growing safety requirements and the trend of increasing car operation autonomy by reducing driver’s influence. The paper covers the coordinated control operation of three active systems to assess the improvement of vehicle response. Direct yaw control through selective wheel braking (DYC), active front steering control (AFS) and active suspension normal force control (NFC) are included. The control method is fuzzy logic. The modelling is done in Matlab/Simulink, where 14-DOF nonlinear full vehicle model and 3-DOF reference model were introduced. Simulations were done for three manoeuvres: cornering event, single lane change and fishhook manoeuvre, at a speed of 130 km/h and dry road surface with adhesion coefficient of 0.9 was assumed. Coordination was done with adjusting scaling factors for each control. Results show improvements in the transient response behaviour of the vehicle compared with four vehicles: vehicle without any active system, vehicle with coordinated DYC and AFS, vehicle with coordinated DYC and NFC and vehicle with coordinated AFS and NFC. The biggest impact can be seen in results for sideslip angle and roll angle, coordinated cooperative control here gives lowest values in the transient period during the manoeuvre. Although it gives better results for the other variables as well. The goal of the coordinated cooperative control is fulfilled by improving the stability and handling of the vehicle, which helps the driver to maintain the feeling of manoeuvrability and the sense for the direction of movement of the vehicle. The system for direct yaw control through selective wheel braking has major impact but the coordination with the other two systems lowers the braking force per wheel. The system for active front steering control has lower impact but at lower speeds helps for maintaining better direction of vehicle movement. Considering these three active systems act simultaneously during high speeds and critical manoeuvres next step would be to define sequence of activation depending on the currently measured vehicle behaviour variables.

Transient Response Characteristics and Performance Assessment of a Calorimetric Surface Junction Probe Under Impulsive Thermal Loading

Abstract The measurement of surface temperatures in highly unsteady flow environments is a challenging task pertaining to the need for high-frequency sensors. This paper contains the sequential activities related to a fast response thermal probe (coaxial surface junction probe—CSJP). This probe is prepared in the laboratory, and its salient features are explored for short-duration (∼20 ms) experiments. The surface junction morphology and inside texture of the probe are examined under field emission scanning electron microscope (FESEM). The study confirms the plastic deformation of thermo-elements with an average junction thickness of 21 μm. The static calibration of the probe using a glycerin bath shows a linear trend between voltage and temperature from which the sensitivity value is calculated as 59 μV/°C. The “thermal product” of the probe is also measured experimentally through the “water droplet technique,” and its value is found to be 8677 J/m2 s0.5 K. The concept of one-dimensional heat flux modeling is followed to infer surface heat flux from transient temperatures. For assuring prediction of heat flux, the probe is calibrated experimentally by exposing to a laser source of known wattage (2 W and 3 W). These findings are also supported by numerical simulation of the probe with accuracy in prediction for surface temperature and heat flux as ± 2% and ±3%, respectively. The performance capability of the probe is demonstrated through shock-tube flow experiments to measure instantaneous heat flux. The comparison of the transient response behavior (9500 K/s) with pressure transducer justifies the utility of the probe under hostile flow environment.

L1 adaptive controller for unmanned surface vehicle type monohull LSS01 autopilot system and guidance design

The control technology grows rapidly at present, especially in the field of autonomous vehicles. This research presents the application of an L1 adaptive controller to an autopilot system and guidance design for an Unmanned Surface Vehicle (USV). The purpose of the L1 adaptive controller deals with how the adaptive control technology solve the problems related to the performance, robustness, and the time adaptability in the issues of uncertainty conditions. The dynamic behaviors of the USV are modeled with 3 degrees of freedom movement in the planar field, where disturbances are applied onto the system. The parameter values of the vessel will be inserted into the state space dynamic equation. The transient response behavior of the system will be analyzed to show the vessel’s movement through the desired waypoints. The L1 adaptive controller method has a fast adaptation rate without losing robustness, which provides better stability using Lyapunov analysis and abilities to dampening the high-frequency as the disturbance by adding Low Pass Filter (LPF) on the control law architecture. Besides this, the L1 adaptive control is relatively simple and easy for industrial implementation. The results show the effectiveness of the L1 adaptive controller when applied to the USV guidance system.

Ultra‐Small 2D PbS Nanoplatelets: Liquid‐Phase Exfoliation and Emerging Applications for Photo‐Electrochemical Photodetectors

2D PbS nanoplatelets (NPLs) form an emerging class of photoactive materials and have been proposed as robust materials for high-performance optoelectronic devices. However, the main drawback of PbS NPLs is the large lateral size, which inhibits their further investigations and practical applications. In this work, ultra-small 2D PbS NPLs with uniform lateral size (11.2± 1.7nm) and thickness (3.7± 0.9nm, ≈6 layers) have been successfully fabricated by a facile liquid-phase exfoliation approach. Their transient optical response and photo-response behavior are evaluated by femtosecond-resolved transient absorption and photo-electrochemical (PEC) measurements. It is shown that the NPLs-based photodetectors (PDs) exhibit excellent photo-response performance from UV to the visible range, showing extremely high photo-responsivity (27.81mA W-1 ) and remarkable detectivity (3.96 × 1010 Jones), which are figures of merit outperforming currently reported PEC-type PDs. The outstanding properties are further analyzed based on the results of first-principle calculations, including electronic band structure and free energies for the oxygen evolution reaction process. This work highlights promising applications of ultra-small 2D PbS NPLs with the potential for breakthrough developments also in other fields of optoelectronic devices.

Tuning Rules for a Class of Passivity-Based Controllers for Mechanical Systems

In this paper, we propose several rules to tune the gains for a class of passivity-based controllers for nonlinear mechanical systems. Such tuning rules prescribe a desired local transient response behavior to the closed-loop system. To establish the tuning rules, we implement a PID passivity-based controller. Then, we linearize the closed-loop system, and we transform the matrix of the resulting system into a class of saddle point matrices to analyze the influence of the control gains, in terms of the oscillations and the rise time, on the transient response of the closed-loop system. Hence, the resulting controllers stabilize the plant and simultaneously address the performance of the closed-loop system. Moreover, our analysis provides a clear insight into how the kinetic energy, the potential energy, and the damping of the mechanical system are related to its transient response, endowing in this way the tuning rules with a physical interpretation. Additionally, we corroborate the analytical results through the practical implementation of a controller that stabilizes a two degrees-of-freedom (DoF) planar manipulator, where the control gains are tuned following the proposed rules.

Transient dynamic response of doubly curved laminated composite shells under pulse loading

Transient response behavior of laminated doubly curved shells with varying geometry and boundary conditions subjected to various time-dependent pulse loads is investigated using Higher order Shear Deformation Theory (HSDT) in the present study. The ratio of thickness co-ordinate to radius of shell (z/R) is incorporated in the mathematical formulation based on HSDT. The condition of zero transverse shear stresses at free surfaces of laminated shell is also included in the displacement function. A C0 finite element formulation using eight noded isoparametric shell element with seven degrees of freedom per node is applied to evaluate the dynamic response of shells. Three types of pulse loading such as sine, triangular and rectangular pulses are considered for the present investigation. Newmark's β method is applied to solve the dynamic equilibrium equation of the shells. The accuracy of the present analysis is examined by comparing the results obtained with those available in the published literature. Several numerical examples are illustrated to show the effects of pulse loading and boundary condition on the central displacement and stresses of laminated composite shells.

Nonlinear Dynamics of Temperature-Dependent FG-GRC Laminated Beams Resting on Visco-Pasternak Foundations

This paper studies the nonlinear dynamic responses of graphene-reinforced composite (GRC) beams in a thermal environment. It is assumed that a laminated beam rests on a Pasternak foundation with viscosity and consists of GRC layers with various volume fractions of graphene reinforcement to construct a functionally graded (FG) pattern along the transverse direction of the beam. An extended Halpin–Tsai model which is calibrated against the results from molecular dynamics (MD) simulations is used to evaluate the material properties of GRC layers. The mechanical model of the beam is on the establishment of a third-order shear deformation beam theory and includes the von-Kármán nonlinearity effect. The model also considers the foundation support and the temperature variation. The two-step perturbation technique is first applied to solve the beam motion equations and to derive the nonlinear dynamic load–deflection equation of the beam. Then a Runge–Kutta numerical method is applied and the solutions for this nonlinear equation are obtained. The influence of FG patterns, visco-elastic foundation, ambient temperature and applied load on transient response behaviors of simply supported FG-GRC laminated beams is revealed and examined in detail.