Reduction In Rise Time Research Articles

Efficient DC motor speed control using a novel multi-stage FOPD(1 + PI) controller optimized by the Pelican optimization algorithm.

This paper introduces a novel multi-stage FOPD(1 + PI) controller for DC motor speed control, optimized using the Pelican Optimization Algorithm (POA). Traditional PID controllers often fall short in handling the complex dynamics of DC motors, leading to suboptimal performance. Our proposed controller integrates fractional-order proportional-derivative (FOPD) and proportional-integral (PI) control actions, optimized via POA to achieve superior control performance. The effectiveness of the proposed controller is validated through rigorous simulations and experimental evaluations. Comparative analysis is conducted against conventional PID and fractional-order PID (FOPID) controllers, fine-tuned using metaheuristic algorithms such as atom search optimization (ASO), stochastic fractal search (SFS), grey wolf optimization (GWO), and sine-cosine algorithm (SCA). Quantitative results demonstrate that the FOPD(1 + PI) controller optimized by POA significantly enhances the dynamic response and stability of the DC motor. Key performance metrics show a reduction in rise time by 28%, settling time by 35%, and overshoot by 22%, while the steady-state error is minimized to 0.3%. The comparative analysis highlights the superior performance, faster response time, high accuracy, and robustness of the proposed controller in various operating conditions, consistently outperforming the PID and FOPID controllers optimized by other metaheuristic algorithms. In conclusion, the POA-optimized multi-stage FOPD(1 + PI) controller presents a significant advancement in DC motor speed control, offering a robust and efficient solution with substantial improvements in performance metrics. This innovative approach has the potential to enhance the efficiency and reliability of DC motor applications in industrial and automotive sectors.

Advanced Flowrate Control of Petroleum Products in Transportation: An Optimized Modified Model Reference PID Approach

Efficient flowrate control is paramount for the seamless operation and reliability of petroleum transportation systems, where precise control of fluid movement ensures not only operational efficiency but also safety and cost-effectiveness. The main aim of this paper is to develop a highly effective modified model reference PID controller, tailored to ensure optimal flowrate control of petroleum products throughout their transportation. Initially, the petrol transportation process is analyzed to establish a suitable mathematical model based on vital factors like pipeline diameter, length, and pump attributes. However, using a basic first-order time delay model for petrol transportation systems is limiting due to inaccuracies, variable delay issues, safety oversights, and real-time control complexities. To improve this, the delay portion is approximated as a third-order transfer function to better reflect complex physical conditions. Subsequently, the PID controller is synthesized by modifying its structure to address flowrate control issues. These modifications primarily focus on the controller’s derivative component, involving the addition of a first-order filter and alterations to its structure. To optimize the proposed controller, the genetic, black hole, and zebra optimization techniques are employed, aiming to minimize an integral time absolute error cost function and ensure that the outlet flow of the controlled system closely follows the response of an appropriate reference model. They are chosen for their proficiency in complex optimization to enhance the controller's effectiveness by optimizing parameters within constraints, adapting to system dynamics, and ensuring optimal conditions. Through simulations, it is demonstrated that the proposed controller significantly enhances the stability and efficiency of the control system, while maintaining practical control signals. Moreover, the proposed modifications and intelligent tuning of the PID controller yield remarkable improvements compared to previous related work, resulting in a 36% reduction in rise time, a 63% reduction in settling time, an 80% reduction in overshoot, and a 98% reduction in cost value.

Analysis of the sharpening effect in gyromagnetic nonlinear transmission lines using the unidimensional form of the Landau-Lifshitz-Gilbert equation.

Continuous nonlinear transmission lines (NLTLs), also known as gyromagnetic lines, consist of ferrite-based magnetic cores biased by an external magnetic field. Over the past years, many analytical and experimental studies have predicted the rise time reduction of the input pulse to the range of a few nanoseconds or even hundreds of ps experimentally observed in such gyromagnetic lines. This effect, known as pulse sharpening, is investigated in this paper built on a model based on a periodic structure of inductive-capacitive cells in series with magnetization-driven voltage sources expressed by the one-dimensional form (1D) of the Landau-Lifshitz-Gilbert (LLG) gyromagnetic equation. We explore the model through parametric study under various input-pulse parameters to understand the physics behind the ferrimagnetic material responses. Moreover, the numerical results obtained from computational simulations using Mathematica (v. 12.1) show how the line parameters (input voltage, damping constant, saturation magnetization, and length) affect the sharpening effect, which is quantified by the switching time. Our results on ferrite-loaded coaxial lines have confirmed many results found in the literature. We validated with a good agreement the proposed model with the result obtained by Dolan in 1993 using the same 1D form of the LLG equation, thus showing that the model proposed here is suitable to quantify the sharpening effect produced by a gyromagnetic NLTL.

A novel fuzzy logic scheme for PID controller auto-tuning

This paper presents a novel method for PID (proportional–integral–derivative) controller auto-tuning based on expert knowledge incorporated into a fuzzy logic inference system. The proposed scheme iteratively tries to improve the performance of the closed-loop system. As performance measures, the proposed scheme uses the characteristics of the step response (rise time, overshoot, and settling time). PID parameters in the first iteration can be calculated based on the basic open-loop step response experiment or it is possible to use current parameters. In each successive iteration, step response characteristics are measured and the relative changes expressed in the percentage of value in the first iteration are calculated and converted into linguistic values. The fuzzy expert system computes fuzzy values that are used after defuzzification as multiplying factors for current PID parameters. To achieve a balance between the aggressive and robust closed-loop response, as well as between the slower and the faster one, the fuzzy expert system works in three operating modes: the one for speeding up the system, the one for reducing the overshoot, and the one for a balanced reduction of rise time and overshoot. The performance and robustness are verified by computer simulation using an extensive range of different processes.

DTC with fuzzy logic for multi-machine systems: traction applications

In this work, a direct torque control (DTC) method for multi-machine systems is applied to electric vehicles (EVs). Initially, the DTC control method associated with the model reference adaptive system (MRAS) is used for speed control, and management of the magnetic quantities is ensured by the variable master-slave control (VMSC). In order to increase the technical performance of the studied system, a DTC method has been associated with a fuzzy logic approach. These two control methods are applied to the traction chain of an electric vehicle to highlight its speed, precision, stability, and robustness metric during particular stress tests imposed on the wheel motor. The results obtained in MATLAB/Simulink software made feasible a comparison of two proposed methods based on their technical performances. It should be noted that the direct fuzzy logic torque control (DFTC) has better performance than the DTC associated with the MRAS system as a rise time reduction of 1.4%, an oscillation of torque, and flux amplitude of less than 9%, static steady-state error near zero. The DTFC control method responds favorably to electric vehicle traction chain systems by the nature of the comfort and safety provided.

Role of Fluorescent Material on Electro-optical Performance of PDLC Devices

ABSTRACT We investigated the effects of fluorescent material doping on the morphology, electro-optical, and fluorescence properties of PDLC films. The acrylate-based PDLC films prepared by polymerisation induced phase separation via UV curing method were doped with fluorescent material. The impact of fluorescent material on the microstructure was studied using scanning electron microscopy. The effect of fluorescent material on the electro-optical properties of PDLC films was studied by liquid crystal composite parameter tester. The electro-optical study revealed that the addition of fluorescent material results in the reduction of rise time, threshold voltage. The development of fluorescent material doped PDLC films with faster rise time, lower threshold voltage and lower saturation voltage will significantly enhance the potential technological applications of PDLC-based devices for smart windows, sensors and flexible devices.

Effects of cesium content on the triple-cation lead halide perovskite photodetectors with enhanced detectivity and response time

This research reports on the effects of Cs doping in the Csx(FA0.75MA0.25PbI3)1−x based perovskites and photodetectors (PDs) with various Cs contents from 0% to 7.5%. The incorporation of 2.5–5% Cs markedly improved the crystal quality of perovskite films that in turns increased, the photoluminescence, absorbance, and quantum efficiency. Over-doping Cs upto 7.5% degraded the devices. X-ray photoemission spectroscopy shows that the binding energies of the Cs, Pb and I core levels shifted to high-energy side, indicating the Cs enter the lattice sites and improved the stability of the film. For PD applications, the influence of Cs doping in the perovskite was mostly on the reduction of rise time, causing by increase of the generation rate of carriers and reduction of trap densities of carriers. The 5% Cs-doped sample showed the best performance, because of the optimization of the grain size, crystal quality and trap density. As a result, the self-powered perovskite demonstrated an impressive performance with ~70% external quantum efficiency, 0.36 A W−1 responsivity, 1.15 × 1012 Jones, and rapid rise and decay time of 1.5 μs and 21 μs, respectively.

Role of BaTiO3 nanoparticles on electro-optic performance of epoxy-resin-based PDLC devices

ABSTRACT The physical properties of polymer dispersed liquid crystals (PDLC) can be tuned as per the application requirement by controlling their composition ratio and microstructure. The addition of nanoparticles is the most convenient method to engineer the properties of PDLCs. This paper investigates the effects of barium titanate (BaTiO3) nanoparticle doping on the morphology, electro-optic, and optical properties of PDLC films. The epoxy resins based PDLC films prepared by polymerisation induced phase separation via heat curing method are doped with BaTiO3 nanoparticle for the first time. The impact of BaTiO3 nanoparticle on the microstructure was studied using polarising optical microscopy and scanning electron microscopy. The electro-optic study reveals that the addition of BaTiO3 nanoparticle results in the reduction of rise time, threshold voltage, saturation voltage and enhancement in the contrast ratio. The doping also results in a decrement of the off-state transmittance curve and an increment in the UV-Visible absorption spectrum. The development of BaTiO3 doped PDLC films with faster rise time, lower threshold voltage, lower saturation voltage and better contrast ratio will significantly enhance the potential technological applications of PDLC-based devices for smart windows, sensors and flexible devices.

Experimental Realization of Constrained Optimization of Sliding Mode Controller Parameters with Modified Objective Functions

An appropriately tuning of Sliding Mode Control (SMC) can be used to overcome the weaknesses like sensitivity to parameter variations, modeling errors and external disturbances. In this research article, Non-Dominated Sorting Genetic Algorithm (NSGA-II) based SMC with modified objective function and the best weight values have been evaluated to improve the performance of closed-loop level control system. Equivalent weights and importance weights are assigned to each term of an objective function based on the standard deviation and percentage contribution of the terms. The stability of the closed-loop system satisfies the Lyapunov stability criteria. The experimental results are conferred and compared with Proportional-Integral-Derivative (PID) controller, conventional SMC and NSGA-II algorithm based SMC. Realistic conditions are used for testing the robustness of the controller. Reduction in rise time, settling time, reaching time, response time and delay in the output is achieved using NSGA-II based SMC. The experimental results demonstrate that NSGA-II based SMC strategy provides better set-point tracking performance and the disturbance rejection capability. Keywords: Non-Dominated Sorting Genetic Algorithm-II, Proportional-Integral-Derivative controller, Sliding mode controller, Multi-objective optimization, Real-time experimentation. Cite this Article: Laware A. R., Talange D. B., Bandal V. S. Experimental Realization of Constrained Optimization of Sliding Mode Controller Parameters with Modified Objective Functions. International Journal of Software Computing and Testing. 2020; 6(1): 8–25p.

Impact of channel thickness and spacer length on logic performance of p-Ge/n-Si hybrid CMOSFETs for ULSI applications

We investigate the logic performance of hybrid (H) CMOS devices comprising Ge p-MOSFETs and Si n-MOSFETs in terms of rise time, fall time, propagation delay and noise margins using extensive numerical device simulation. We analyse CMOS devices featuring channel thickness (Tch) ranging 5–10 nm, spacer length (Lsp) from 1 to 10 nm at channel length (Lg) of both 20 and 30 nm. Our investigation reveals that hybrid CMOS inverters exhibit reduction in rise time and propagation delay by 53.5% and 31.6% as compared with the corresponding Si value, respectively for the ratio of widths of p- and n-MOSFETs (r) = 3, Tch = 7 nm and Lsp = 5 nm at Lg = 20 nm. Furthermore, the frequency of oscillations of a 3-stage ring oscillator constructed with hybrid CMOSFETs shows a significant improvement of 151.7% at Lg = 20 nm for r = 1, over its equivalent Si counterpart.

Rise time reduction of thermal actuators operated in air and water through optimized pre-shaped open-loop driving

Electrothermal actuators have many advantages compared to other actuators used in micro-electro-mechanical systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10–90% rise time of 85 μs in air and 234 μs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10–90% rise time from 85 μs to 3 μs in air and from 234 μs to 5 μs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

Extremum Seeking-Based Optimization of High Voltage Converter Modulator Rise-Time

We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center by iteratively, simultaneously tuning the first eight switching edges of each of the three-phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half, compared to the 100 μs achieved at the Spallation Neutron Source at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60-Hz repetition rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.

Postnatal maturation of GABAergic transmission in the rat basolateral amygdala.

Many psychiatric disorders, including anxiety and autism spectrum disorders, have early ages of onset and high incidence in juveniles. To better treat and prevent these disorders, it is important to first understand normal development of brain circuits that process emotion. Healthy and maladaptive emotional processing involve the basolateral amygdala (BLA), dysfunction of which has been implicated in numerous psychiatric disorders. Normal function of the adult BLA relies on a fine balance of glutamatergic excitation and GABAergic inhibition. Elsewhere in the brain GABAergic transmission changes throughout development, but little is known about the maturation of GABAergic transmission in the BLA. Here we used whole cell patch-clamp recording and single-cell RT-PCR to study GABAergic transmission in rat BLA principal neurons at postnatal day (P)7, P14, P21, P28, and P35. GABAA currents exhibited a significant twofold reduction in rise time and nearly 25% reduction in decay time constant between P7 and P28. This corresponded with a shift in expression of GABAA receptor subunit mRNA from the α2- to the α1-subunit. The reversal potential for GABAA receptors transitioned from depolarizing to hyperpolarizing with age, from around -55 mV at P7 to -70 mV by P21. There was a corresponding shift in expression of opposing chloride pumps that influence the reversal, from NKCC1 to KCC2. Finally, we observed short-term depression of GABAA postsynaptic currents in immature neurons that was significantly and gradually abolished by P28. These findings reveal that in the developing BLA GABAergic transmission is highly dynamic, reaching maturity at the end of the first postnatal month.

Electrodynamic Simulation of High-Voltage Peaking Switch

This paper discusses the modeling of a peaking switch to study the reduction in rise time for the subnanosecond duration pulses. The effect of the various shapes of input pulse, inductance, and interelectrode distance on the output voltage and wave shape is discussed in this paper. The modeling has been carried out using the electromagnetic and microwave modeling software of Computer Simulation Technology.

Partial discharge characteristics of interturn insulation used for inverter-fed traction motor under bipolar impulses

Inverter-fed traction motors, which are employed for electric-multiple-units (EMUs), are subjected to Pulse Width Modulated (PWM) impulse voltage. Impulse voltage has fast rise/fall time and high repetition frequency. The failure mechanism of insulation under impulses is different from that of standard 50 Hz sinusoidal condition. Partial discharge (PD) characteristics (discharge number, mean discharge quantity and phase resolved partial discharge (PRPD) pattern) with different frequencies and different rise times of impulse voltage were investigated. The results reveal that discharge number and mean discharge quantity increase, while PRPD pattern moves to the zero of impulse voltage with decrease of rise time. Discharge number and PRPD pattern follow that trend with increase of frequency, the value of mean discharge quantity is similar. Memory effect of the deposited space charges on PD was studied. PRPD pattern moves to the zero of bipolar impulse voltage due to the role of space charges, with increase of frequency and decrease of rise time. It is revealed that available discharge time is prolonged and overvoltage across the cavity increases with augment of frequency, which results in discharge number increasing. Under the condition of shortening the rise time, with the same statistical time lag tL, ∆V would increase if dV/dt is higher, which results in enhancement of discharge quantity. Discharge number increases with reduction of rise time, because the decreased multiple of td is lower than the increased multiple of dV/dt. Study of PD characteristics and role of space charges is helpful to the exploration of the destructive mechanism of insulating materials under bipolar impulse. partial discharges, bipolar impulse, interturn insulation, electric-multiple-units, memory effect, space charges

The effect of different rise time on partial discharge activity of inter-turn insulation under square wave voltage

SUMMARY Partial discharge (PD) activity of the inter-turn insulation of electric motor winding is investigated under different rise time of the square wave voltage, and the superposition effect of the polarized charges on PD activity is also analyzed for the specimen. Under different rise time of the square wave, tests of the PD activity (e.g., PD inception voltage (PDIV) and phase resolved PD (PRPD) pattern) and the thermal stimulated depolarization current are both performed. Comparing the results of the PRPD patterns at different rise time of the square wave, most of PD moves to the zero point of square wave voltage with the reduction in rise time. Also, PDIV decreases with the reduction in rise time. Through the analysis of a complete polarization process at the square wave voltage, the superposition effect of the polarized charges leads to the enhancement of electric field in the specimen when the polarity of square wave voltage rapidly reverses. With the reduction in rise time at square wave, more polarized charges can not follow changes of the applied voltage since the relaxation time of these dipoles is longer than the rise time of square wave, which leads to the enhancement of the electric field across a cavity. For this reason, they result in the reduction in PDIV and the movement of PRPD patterns to zero point of square wave voltage. Copyright © 2012 John Wiley & Sons, Ltd.

Signal coupling and signal integrity in multi-strip resistive plate chambers used for timing applications

We have systematically studied the transmission of electrical signals along several 2-strip Resistive Plate Chambers (RPCs) in the frequency range f=0.1−3.5GHz. Such a range was chosen to fully cover the bandwidth associated to the very short rise-times of signals originated in RPCs used for sub-100ps timing applications. This work conveys experimental evidence of the dominant role of modal dispersion in counters built at the 1m scale, a fact that results in large cross-talk levels and strong signal shaping. It is shown that modal dispersion appears in RPCs due to their inherent unbalance between capacitive and inductive coupling. A practical way to restore this symmetry has been introduced (hereafter 'electrostatic compensation’), allowing for a cross-talk suppression factor up to ×12 and a rise-time reduction by 200ps. Under conditions of compensation the signal transmission is only limited by dielectric losses, yielding a length-dependent cutoff frequency of around 1GHz for propagation along 2m in typical float glass-based RPCs.It is further shown that 'electrostatic compensation’ can be achieved for an arbitrary number of strips as long as the nature of the coupling is 'short-range’, that is an almost exact assumption for typical strip-line RPCs. This work extends the bandwidth of previous studies by a factor of×20.

Partial Discharge Activity of Inter-turn Insulation under Different Parameters of Square Wave Voltage

Partial discharge (PD) activity of inter-turn insulation of electric motor winding is investigated under different parameters of square wave voltage, and the memory effect of deposited space charge in a cavity on PD activity is also studied. Under different frequency and rise time of square wave, discharge number, maximum discharge magnitude and phase resolved PD pattern is investigated. Increase in frequency and decrease in rise time both results in increase in maximum discharge magnitude and discharge number at square wave. Comparing the results of phase resolved PD patterns at different frequency of square wave, most of PD moves to zero point of square wave voltage with the increase in frequency. Meanwhile, with the reduction in rise time of square wave, a similar phenomenon can be observed. Through the analysis of a PD process at square wave voltage, the memory effect of deposited space charge after a discharge in cavity leads to superposition of electric field when the polarity of square wave voltage rapidly reverses. With the increase in frequency and reduction in rise time at square wave, superposition of electric field enhances. As a result, available discharge time prolongs during the rise time of square wave and overvoltage across the cavity increases. They result in the increase in discharge number and maximum discharge magnitude. Furthermore, for this reason, the position of PD shifts to zero point of square wave voltage.

Near-fault strong motion complexity of the 2000 Tottori earthquake (Japan) from a broadband source asperity model

The October 6/2000 Tottori earthquake that occurred in central Japan was an intermediate size strike-slip event that produced a very large number of near field strong motion recordings. The large amount of recorded data provides a unique opportunity for investigating a source asperity model of the Tottori earthquake that, combined with a hybrid strong motion simulation technique, is able to reproduce the observed broadband frequency near-fault ground motion. We investigated the optimum source asperity parameters of the Tottori earthquake, by applying a Genetic Algorithm (GA) inversion scheme to optimise the fitting between simulated and observed response spectra and Peak Ground Acceleration (PGA) values. We constrained the initial model of our inversion by using the heterogeneous slip distribution obtained from a kinematic inversion of the source of previous studies. We used all the observed near-fault ground motions (−100 m) from the borehole strong motion network of Japan (KiK-Net), which are little affected by surficial geology (site effects). The calculation of broadband frequency strong ground motion (0.1–10 Hz) is achieved by applying a hybrid technique that combines a deterministic simulation of the wave propagation for the low frequencies and a semi-stochastic modelling approach for the high frequencies. For the simulation of the high frequencies, we introduce a frequency-dependent radiation pattern model that efficiently removes the dependence of the pattern coefficient on the azimuth and take-off angle as the frequency increases. The good agreement between the observed and simulated broadband ground motions shows that our inversion procedure is successful in estimating the optimum asperity parameters of the Tottori earthquake and provides a good test for the strong ground motion simulation technique. The ratio of background stress drop to average asperity stress drop from our inversion is nearly 50%, in agreement with the theoretical asperity model of Das and Kostrov [Das, S., Kostrov, B.V., 1986. Fracture of a single asperity on a finite fault: a model for weak earthquakes? Earthquake Source Mechanics, AGU, pp. 91–96.], and an empirical ratio of asperities to rupture area [Seismol. Res. Lett. 70 (1999) 59–80.]. The simulated radiation pattern is very complex for epicentral distances within half the fault length, but it approaches the radiation of a double-couple point source for larger distances. The rupture velocity and rise time have a significant influence on the Peak Ground Velocity (PGV) distribution around the fault. An increase in rupture velocity produces a similar effect on the ground motion as a reduction in rise time.

Rise time reduction in high-voltage pulse transformers using auxiliary windings

Today high-voltage pulses are reaching more fields of application. High-voltage pulse transformers are often used in association with high-voltage pulse generating circuits to further increase the pulse output voltage level. However, because of the transformer parasitic elements involved, the transformer is the critical device in shaping the rising characteristics of the output pulse. One of the techniques usually adopted to decrease the leakage inductance of the transformer adds two auxiliary windings to the transformer. If properly used, these auxiliary windings reduce the leakage flux and, therefore, the leakage inductance. As a result the pulse rise time is reduced. In this paper, a mathematical model is used to describe the observed behavior of a transformer operating with auxiliary windings, based on the theory of electromagnetic coupled circuits. The model is discussed regarding the experimental results obtained from a high-voltage test transformer associated with a high-voltage pulse generating circuit, and the simulation results obtained from the numerical evaluation of the developed differential equations implemented in Matlab/Simulink with the measured transformer parameters.