Steady-state Output Research Articles

Collective resonant behaviors in two coupled fluctuating-mass oscillators with tempered Mittag-Leffler memory kernel

In this study, we propose the coupled fluctuating-mass oscillators with a tempered Mittag-Leffler (M-L) memory kernel, and investigate the collective resonant behaviors. Using the stochastic average method, we acquire the analytical expression of steady-state output amplitude. Based on numerical results, we further study the dependence on various system parameters in detail, and find that coupling strength, memory exponent and memory time exert different effects on the non-monotonic behaviors. We also observe that stochastic resonance (SR) in the wide sense occurs in the coupled system. These results can provide more extensive support for manipulating the collective behaviors in the potential applications.

Self-terminating barium ion laser at 614.2 nm

Experimental results of the laser operating on the barium ion self-terminating transition 6p2P3/2o - 5d2D5/2 at λ=614.2 nm investigations are presented. Through a series of tests, we demonstrated a significant improvement of the output characteristics of this laser by employing (i) a novel high-voltage nanosecond switch capable to operate at high pulse repetition frequency (more than 50 kHz), and (ii) hydrogen addition to the active medium. Achieved steady-state average output power in the burst-mode operation amounted to 125 mW with laser pulse duration of ≈5 ns at half-maximum.

Simulation analysis of transient output characteristics of inverter with asynchronous motor load based on second-order filtering link

Based on the voltage and current oscillation characteristics of the second-order filtering link, an LC boundary condition analysis method for the steady-state and transient minimum output power of the inverter power supply for asynchronous motor drive based on the concept of dynamic capacitive and inductive coefficients is proposed. For three typical motor topologies below 100 kW class, a dynamic equivalent resistive model based on turndown rate - input frequency is established and its starting transient and speed steady-state resistive characteristics are analyzed. On this basis, the dynamic capacitance coefficient-current amplification curve and dynamic inductance coefficient-voltage amplification curve are introduced, and the optimal (C,L) combination solution is extracted by data screening and 3D fitting to control the inverter output current inrush while improving the voltage utilization efficiency. The optimal (C,L) combination solution is extracted by data filtering and 3D fitting to control the inverter output current inrush while improving the voltage utilization efficiency. The image2data tool is used to compare and analyze the characteristics of second-order filtering parameters selection under two common strategies of specific harmonic cancellation pulse-width modulation (SHEPWM) and triangular carrier pulse-width modulation (TCPWM) for motor drives, and introduce the device voltage distortion model to improve the system accuracy. It is found that the output power of SHEPWM is about 0.03% higher than that of TCPWM under the same loading condition, and the obtained boundary LC parameters can simultaneously meet the transient starting power requirement of the motor and optimize the output efficiency of the inverter at steady state speed.

Intra-industry trade, involuntary unemployment and macroeconomic stability

We introduce taste for variety in a one-sector model of differentiated products with productive labor externalities, considering two OLG countries, one with wage rigidity and the other with full employment. After opening the borders to capital mobility and intra-industry trade, steady state output and real wages improve in the full employment country and the saddle path stability, characterizing this country under autarky, will prevail in the globalized world if this economy is big enough. Unemployment increases in the country with wage rigidity and, for intermediate plausible values of both the current propensity to consume and of the labor externality, indeterminacy, which emerges in the rigid wage economy in autarky, will be exported to the world if this country is relatively big. Finally, we show that globalization leads to the appearance of stable deterministic cycles in activity, employment and the trade account, both through flip and Hopf bifurcations, when the world steady state is locally determinate, for empirically plausible low degrees of labor externalities. This implies that trade cycles occur in the absence of shocks to fundamentals, and even without uncertainty in expectations.

Stable 2 W continuous-wave 261.5 nm laser for cooling and trapping aluminum monochloride.

We present a high-power tunable deep-ultraviolet (DUV) laser that uses two consecutive cavity enhanced doubling stages with LBO and CLBO crystals to produce the fourth harmonic of an amplified homebuilt external cavity diode laser. The system generates up to 2.75 W of 261.5 nm laser light with a ∼2 W stable steady-state output power and performs second harmonic generation in a largely unexplored high intensity regime in CLBO for continuous wave DUV light. We use this laser to perform fluorescence spectroscopy on the A1Π ← X1Σ+ transition in a cold, slow beam of AlCl molecules and probe the A1Π|v' = 0, J' = 1〉 state hyperfine structure for future laser cooling and trapping experiments. This work demonstrates that the production of tunable, watt-level DUV lasers is becoming routine for a variety of wavelength-specific applications in atomic, molecular and optical physics.

Characterization of subunit interactions in the hetero-oligomeric retinoid oxidoreductase complex.

The hetero-oligomeric retinoid oxidoreductase complex (ROC) catalyzes the interconversion of all-trans-retinol and all-trans-retinaldehyde to maintain the steady-state output of retinaldehyde, the precursor of all-trans-retinoic acid that regulates the transcription of numerous genes. The interconversion is catalyzed by two distinct components of the ROC: the NAD(H)-dependent retinol dehydrogenase 10 (RDH10) and the NADP(H)-dependent dehydrogenase reductase 3 (DHRS3). The binding between RDH10 and DHRS3 subunits in the ROC results in mutual activation of the subunits. The molecular basis for their activation is currently unknown. Here, we applied site-directed mutagenesis to investigate the roles of amino acid residues previously implied in subunit interactions in other SDRs to obtain the first insight into the subunit interactions in the ROC. The results of these studies suggest that the cofactor binding to RDH10 subunit is critical for the activation of DHRS3 subunit and vice versa. The C-terminal residues 317-331 of RDH10 are critical for the activity of RDH10 homo-oligomers but not for the binding to DHRS3. The C-terminal residues 291-295 are required for DHRS3 subunit activity of the ROC. The highly conserved C-terminal cysteines appear to be involved in inter-subunit communications, affecting the affinity of the cofactor binding site in RDH10 homo-oligomers as well as in the ROC. Modeling of the ROC quaternary structure based on other known structures of SDRs suggests that its integral membrane-associated subunits may be inserted in adjacent membranes of the endoplasmic reticulum (ER), making the formation and function of the ROC dependent on the dynamic nature of the tubular ER network.

Molten-Salt-Assisted CsPbI3 Perovskite Crystallization for Nearly 20%-Efficiency Solar Cells.

Dynamic manipulation of crystallization is pivotal to the quality of polycrystalline films. A molten-salt-assisted crystallization (MSAC) strategy is presented to improve grain growth of the all-inorganic perovskite films. Compared with the traditional solvent annealing, MSAC enables more intensive mass transfer by means of convection and diffusion, which is beneficial to the interaction among the precursor colloids and to inducing in-plane growth of perovskite grains, resulting in the formation of high-quality perovskite films with suppressed pinhole and crack formation. Additionally, the introduction of molten salt alters the intermediate phases, and thus changes the crystallization pathways by reducing the energy barrier to produce films with desired optical and electrical properties. As a result, the MSAC strategy endows the devices with champion steady-state output efficiency of 19.83% and open-circuit voltage (Voc ) as high as 1.2V, among the highest for this type of solar cell, thanks to its effectively reduced Voc deficit.

Examining the Economic Optimality of Automatic Generation Control

The automatic generation control (AGC) system is temporally situated between economic dispatch and synchronous generator dynamics, and its primary role is to regulate frequency within and tie-line flows between control areas. Given appropriate choice of participation factors (feed-forward controller gains that govern the disaggregation of the area-level power requirement to individual generators), the AGC can be engineered to nudge system dynamics toward a steady-state operating point corresponding to economic optimality. This paper establishes necessary and sufficient conditions under which a widely accepted choice of participation factors guarantees the alignment of steady-state synchronous generator outputs with a global minimum of a prototypical economic dispatch problem. In so doing, it resolves several ambiguities and formalizes technical assumptions governing the role of the standard AGC architecture in the context of economic dispatch and steady-state operation. Numerical case studies tailored to a modified version of the New England 39-bus 10-machine test system validate the theoretical results.

Captive power, market access and macroeconomic performance: Reforming the Bangladesh electricity sector

Integrating the captive capacity with the on-grid supply has been advocated as a way to improve resource utilization in the electricity market in developing and emerging countries. Despite many countries granting Captive Power Plants (CPPs) access to the grid, integration may still be hindered by other barriers to entry. In Bangladesh, CPPs are required to sell their electricity surplus, but there is no evidence of trading with the national grid, mostly due to high connectivity costs. In this paper we develop and estimate a fit-for-purpose Dynamic Stochastic General Equilibrium (DSGE) model to examine the effects of the Bangladeshi CPPs connecting to the national grid and selling their surplus at regulated prices. The model parameters are set through a combination of calibration and Bayesian estimation. We find that if CPPs are connected to the national grid, steady-state industrial output, GDP, and household consumption decrease due to pre-existing energy price distortions. These results support the second-best theory, which implies that merely connecting the CPPs to the national grid without firstly removing market distortions can lead to economically inefficient outcomes. Instead, government should first consider alternative reforms such as phasing out subsidized tariffs and enabling a competitive market environment.

Harmonic balance analysis of output characteristics of free-standing mode triboelectric nanogenerators

Harmonic balance analysis of the output characteristics of free-standing mode triboelectric nanogenerators (FS-TENG) is conducted in this study. Considering the contact-impact force between the free-standing layer and fixed electrodes, the piecewise linear differential equation of motion of the layer is derived. Combined with an equivalent circuit differential equation, the electromechanical coupling model of the FS-TENG with nonlinear variation in the electrode distance is established. The harmonic balance method and alternate frequency/time domain method are adopted to obtain the steady-state output characteristics of the FS-TENG. The arc-length continuation method is utilized to track the multisolution region owing to bifurcation. The stability of harmonic balance solutions is determined through an eigenvalue analysis in the frequency domain. Both numerical integration and dynamic tests are conducted to verify the accuracy of the harmonic balance analysis. The influence of the nonlinear variation of electrode distance on the output characteristics of the FS-TENG is further examined through comparison with the existing model. Based on these results, the effects of vibration excitation amplitude, contact stiffness, and structural damping on the output characteristics of the system are discussed. The harmonic balance analysis in this study will contribute to the structural optimization design of the FS-TENG and further promote the development of the FS-TENG for engineering practicability.

Steady State Behavior of a Single-Switch Non-isolated DC-DC SEPIC Converter Topology with Improved Static Voltage Gain

This paper presents the analysis of steady state behavior of a single switch non-isolated Single Ended Primary Inductance Converter (SEPIC) topology for achieving high DC voltage gain using diode-capacitor voltage multiplier. A voltage boosting module consisting of inductor and capacitor in addition with two diodes is introduced in the conventional SEPIC configuration in order to derive the DC-DC conversion technology proposed in this work. The voltage gain of the converter is extended using a diode-capacitor voltage multiplier cell. The converter suggested in this work has a single controlled switch. Hence, the conduction losses and the control complexity of the switch are very much reduced. The open loop configuration of the proposed non-isolated converter is described under continuous inductor current mode. The voltage boosting capability of the presented converter is compared with that of the existing modified SEPIC structure. The presented positive output converter topology has low switch voltage-current stress compared to the existing modified SEPIC topology given in the literature. The inductor and capacitor components of the suggested converter are so chosen that the DC output voltage and current waveforms show very low percentage of ripples. A DC voltage level of 24 V is given as input to the proposed converter. The DC voltage obtained across the load terminals is around 370 V which is achievable with low duty ratio (= 0.7) of the active switch. The voltage conversion ratio is very much influenced by the variation of the duty cycle of the power switch. In this work, the converter topology is presented and its various modes of operation are explained with equivalent circuits. The PSIM software platform is effectively and efficiently utilized to validate the performance of the converter. The obtained results convey that the proposed DC-DC conversion technology with extended voltage gain has the capability to maintain the steady-state output voltage and current profiles with almost negligible amount of ripples owing to the use of suitably designed non-dissipative elements in LC filter.

Implementation of non-isolated three-port converter through augmented time response

<p><span lang="EN-US">The work is concerning a multi-port dc-dc converter with improved time response and steady state output. Here the converter carries bare amount of switches for managing the power with mono inductance. The inductance and along with that the switched capacitance are pre owned to bring large voltage gain. This paper put forwarded an appropriate controller for the closed loop monitored high-gain converter with three ports. Higher is that the conversion rate. This converter is also a good interface between DC-source and load that aims to progressing time response with FLC and PI controller in the closed loop system. The converter with the PI controller and FLC is look over and the fast responses are compared with time domain specifications. The simulation outcome indicates that the FLC based converter brings most excellent time domain response.</span></p>

Data-driven inference of high-accuracy isostable-based dynamical models in response to external inputs.

Isostable reduction is a powerful technique that can be used to characterize behaviors of nonlinear dynamical systems using a basis of slowly decaying eigenfunctions of the Koopman operator. When the underlying dynamical equations are known, previously developed numerical techniques allow for high-order accuracy computation of isostable reduced models. However, in situations where the dynamical equations are unknown, few general techniques are available that provide reliable estimates of the isostable reduced equations, especially in applications where large magnitude inputs are considered. In this work, a purely data-driven inference strategy yielding high-accuracy isostable reduced models is developed for dynamical systems with a fixed point attractor. By analyzing steady-state outputs of nonlinear systems in response to sinusoidal forcing, both isostable response functions and isostable-to-output relationships can be estimated to arbitrary accuracy in an expansion performed in the isostable coordinates. Detailed examples are considered for a population of synaptically coupled neurons and for the one-dimensional Burgers' equation. While linear estimates of the isostable response functions are sufficient to characterize the dynamical behavior when small magnitude inputs are considered, the high-accuracy reduced order model inference strategy proposed here is essential when considering large magnitude inputs.

Constrained Least Mean Square Algorithm with Coefficient Reusing

The constrained least mean square (CLMS) algorithm is one of the most popular online linear-equality-constrained beamforming algorithms. This paper demonstrates for the first time that it solves a deterministic minimum-disturbance optimization problem in an exact manner. Such a framework is employed to insert the coefficient reusing technique into the algorithm, engendering a new low-complexity constrained adaptive filter, designated as RC-CLMS, that trades convergence rate for asymptotic performance. A stochastic model that predicts the average evolution of adaptive weights is derived. Through simulations, the advanced reusing coefficient extension of the constrained least mean-square algorithm enhanced the asymptotic signal-to-interference-plus-noise ratio and decreased the steady-state mean output energy. Furthermore, the resulting beam pattern is analyzed with an antenna analysis tool, confirming the efficacy of the advanced algorithm in a realistic setting, when the electromagnetic coupling between the antennas is taken into account.

Wigner negativity in the steady-state output of a Kerr parametric oscillator

The output field from a continuously driven linear parametric oscillator may exhibit considerably more squeezing than the intracavity field. Inspired by this fact, we explore the nonclassical features of the steady-state output field of a driven nonlinear Kerr parametric oscillator using a temporal wave packet mode description. Utilizing a new numerical method, we have access to the density matrix of arbitrary wave packet modes. Remarkably, we find that even though the steady-state cavity field is always characterized by a positive Wigner function, the output may exhibit Wigner negativity, depending on the properties of the selected mode.

Thermal imaging based maximum power point tracking for solar modules in variable ambient temperature

In this study, a thermography based modified perturb & observe maximum power point tracking (P&O MPPT) technique is proposed and implemented to overcome challenges due to unstable environmental temperature and radiance. A temperature based empirical model of PV module is used to approximate the peak power parameters. The objective of using temperature based model is to minimize the difference voltage (∆V) signal which in turn decreases the time to reach maximum power point and hence increases the speed of the MPPT system. Less number of iterations to achieve maximum power point also improves the output signal quality by reducing the number of fluctuations in the signal. Although the temperature based MPPT methods have already been suggested in literature but the novelty of the proposed method lies in using infrared (IR) images to monitor the instant temperature of photovoltaic (PV) module, which give its advantage in the form of fast and stable steady-state output. Results of the proposed scheme are found better when compared to the conventional P&O MPPT.

A theoretical model of the intermittent contact of piezoelectric actuator based on Greenwood-Williamson theory

A theoretical model of the intermittent contact mechanism of linear piezoelectric actuator was proposed, in which the microscopic characteristics of the contact surfaces were taken into account. Greenwood-Williamson (GM) theory was involved for the first time to describe the microscopic characteristics of the contact surfaces in which the contact surfaces were considered as random rough surfaces that were composed of large amounts of asperities and the heights of the asperities conformed to a Gauss distribution. The developed theoretical model gives an insight into the influence of the microscopic properties, as well as the macroscopic and material properties on the output performance of the actuator, which may provide guidance for the design of such type of piezoelectric actuator. During the modeling, normal kinetic contact force, kinetic friction coefficient, friction force and steady-state output force of were obtained in sequence. And some simulations were carried out to analyze how factors such as the type of material, the roughness of the contact surface, the initial distance between the stator and the rotor, and the preload, et.al, affect the contact performance. A set of experiments were carried out to reveal the influence of surface roughness, material type and preload on the steady-state output thrust. The simulated results were found in good agreement with the experiment ones at most of the tested points. Finally, surface roughness of the stator and rotor were tested before and after the operation, which indicated that the rotor and stator had similar roughness after operation.

The VIT Transform Approach to Discrete-Time Signals and Linear Time-Varying Systems

A transform approach based on a variable initial time (VIT) formulation is developed for discrete-time signals and linear time-varying discrete-time systems or digital filters. The VIT transform is a formal power series in z−1, which converts functions given by linear time-varying difference equations into left polynomial fractions with variable coefficients, and with initial conditions incorporated into the framework. It is shown that the transform satisfies a number of properties that are analogous to those of the ordinary z-transform, and that it is possible to do scaling of z−i by time functions, which results in left-fraction forms for the transform of a large class of functions including sinusoids with general time-varying amplitudes and frequencies. Using the extended right Euclidean algorithm in a skew polynomial ring with time-varying coefficients, it is shown that a sum of left polynomial fractions can be written as a single fraction, which results in linear time-varying recursions for the inverse transform of the combined fraction. The extraction of a first-order term from a given polynomial fraction is carried out in terms of the evaluation of zi at time functions. In the application to linear time-varying systems, it is proved that the VIT transform of the system output is equal to the product of the VIT transform of the input and the VIT transform of the unit-pulse response function. For systems given by a time-varying moving average or an autoregressive model, the transform framework is used to determine the steady-state output response resulting from various signal inputs such as the step and cosine functions.

A multipronged core power control strategy for Reaktor TRIGA PUSPATI

At present, the power tracking performance of nuclear Reaktor TRIGA PUSPATI (RTP) is considered unsatisfactory performance due to relatively long settling time during transient and a chattering noise during steady-state power output. Application of the conventional Feedback Control Algorithm (FCA) as a power control technique is proven to be inadequate to keep the core power output stable and within tight multiple parameter constraints for the safety demand of the RTP. Hence, the present study proposed a multipronged core power control strategy improvement through manipulation of the current Control Rod Selection Algorithm (CRSA), Control Rod Speed Design (CRSD), and Power Change Rate Constraint (PCRC) which are part of the core power control design. In this paper, the profiling and analysis of the multipronged core power control strategy are presented. The model for core power control consists of mathematical models of the reactor core, FCA controller, and a series of multipronged models. The mathematical models of the reactor core are based on the point kinetics model, thermal-hydraulic model, and reactivity model. The reactor model is integrated with the FCA controller and a combination of CRSA-CRSD-PCRC models. The power tracking performance of the proposed control strategy and conventional FCA is compared via computer simulation. Overall, the results show the multipronged FCA offers a wider options for optimum operation of the TRIGA reactor.

Numerical investigation on the dynamic response characteristics of a thermoelectric generator module under transient temperature excitations

In this work, a three-dimensional transient numerical model of a thermoelectric generator module considering the temperature-dependent properties and the topological connection of load resistance is proposed to study its dynamic response characteristics. The dynamic output power and conversion efficiency of the thermoelectric generator module under steady and different transient temperature excitations are compared and studied. A time delay exists in the output response of the thermoelectric generator module, and the time delay increases when the temperature rate increases. When the heat source temperature changes rapidly, the corresponding output power, conversion efficiency, and other thermal responses will show a more stable change trend. Moreover, the dynamic response characteristic of the output power is synchronous with that of the conversion efficiency. The periodic temperature excitation may amplify the output power, where the average output power of the sine and triangle waves are 4.93% and 2.82% respectively higher than the steady-state output power. However, the average conversion efficiency of both is almost identical to the steady-state conversion efficiency. The proposed model contributes to predicting the dynamic performance of thermoelectric generators, and can be further extended to the whole thermoelectric generator system.