Complete Compensation Research Articles

Perturbation Observer Based Fractional-Order Control for SMES Systems Based on Jellyfish Search Algorithm

The electric energy storage system (EESS) is considered as an efficient and promising tool to alleviate the power imbalance of grid-connected microgrid with distributed generation (DG). This work develops a perturbation observer-based fractional-order control (POFOC) strategy for superconducting magnetic energy storage (SMES) system. Initially, a high-gain state and perturbation observer (HGSPO) is designed for reliable estimation of the combined impact of the nonlinearities, parameter uncertainties, unmodeled dynamics, and external disturbances of SMES. Then the storage function of an SMES system is designed, which takes favorable terms into serious consideration to sufficiently utilize the physical properties of the SMES system. Moreover, a fractional-order control framework is applied for complete compensation for the estimated perturbation and adopted as the attached input to boost its dynamical responses. Furthermore, a newly proposed jellyfish search algorithm (JSA) is utilized to realize optimization and tuning of control gains of the developed strategy, upon which high-quality global optimum can be obtained to ensure prominent controlling performance. Case studies, e.g., active power and reactive power supply and system restoration capability under power grid fault effectively validate the effectiveness and reliability of the POFOC strategy compared with traditional PID control and interconnection and damping assignment passivity-based controller (IDA-PBC). In particular, the overshoot of PID is 115.264% of the rated value, while POFOC has no overshoot.

Four‐level compensation standards and calculation techniques for water ecological protection in the river source regions in China

AbstractThe water ecological environment problem in water resources management of river basins mainly lies in the incoordination between the utilization and protection of water resources among different regions. Ecological compensation, therefore, is needed in order to solve this problem. The measurement of reasonable compensation standard plays a vitally important role in the successful establishment of ecological compensation. In this study, a four‐level compensation standard called ‘minimum‐basic‐complete‐maximum’ (MBCM) is proposed, which is based on the calculation of direct cost, the equalization of essential public service for water, opportunity loss and the comprehensive benefit of water ecological environment protection in the source region. MBCM method provides a multi‐level platform for the establishment of the compensation mechanism, which enables different departments to know their respective costs and benefits clearly. The Sanjiangyuan region (SR) in China is chosen as the study area. The results show that (1) the minimum compensation standard for the SR is 300 million RMB per year; (2) the basic compensation standard is 1.7 billion RMB per year; (3) the complete compensation standard is about 3.75 billion RMB per year; (4) the maximum compensation standard creates the total economic value of 181.6 billion RMB for the downstream water output. The proposed MBCM four‐level compensation standard can also be applied to other river source regions.

Mesoscale analysis on clusters in conjunction with fast fluidized bed modeling

As a subsequent paper for “type-A-choking-oriented unified model for fast fluidization dynamics”, the present work aims to provide more systematic mesoscale analyses on clusters. Starting from theoretical derivations on idealized flow patterns of gas and solids around a single falling cluster; the momentum consumption due to particle circulation in clouds and the modification of flows by the constraint of driving force available in the bed were addressed. Complete compensation of the pressure-drop driven percolated gas in clusters by the reversely-penetrating particles was used for the ultimate closure of the model. An important finding of the present work, different from most empirical correlations, but verified by Wei and Zhu's latest experimental data and others, is that the cluster diameter does not vary monotonically with the mean solids holdup of the bed, but has a maximum value in between. Demonstrative calculations show that it is easy for Group A particles to enter the flow regime of high-density fast-fluidization as the circulating solids flux increases continuously, while fast fluidization for Group B particles tends to be stopped at Type C choking in advance. Compared with Group A particles, the clusters for Group B particles are less dense, but the penetration velocities of particles are higher, resulting in much larger dimensionless diameters of clusters. Finally, issues of pseudo-2D fast-bed modeling were discussed, and modeling of fast-beds with uneven flow fields was outlook briefly.

Neural network approximation-based backstepping sliding mode control for spacecraft with input saturation and dynamics uncertainty

This paper proposed a neural network approximation-based backstepping sliding mode control approach (NN-BSMC) to address the problem of attitude tracking control for spacecraft in the presence of inertial uncertainties, external disturbances and input saturation. First, the attitude dynamics model of the spacecraft is presented, and the error dynamics model with input saturation is derived. Second, a control scheme using sliding mode control (SMC) and backstepping technique is proposed to guarantee the robustness against the dynamics uncertainty and deal with the effect of input saturation. Under this framework, a neural network (NN) approximator is developed to online estimate the dynamics uncertainty of the spacecraft. Adaptive laws are designed to update the NN weight and estimate the unknown bound of approximation error. The control law does not require the prior knowledge about the bounds on the uncertainty and can provide complete compensation for the uncertainty. Moreover, a Lyapunov-based approach is employed to prove the global stability of the closed-loop system and the asymptotical convergence of the attitude tracking errors. Finally, numerical simulations are carried out to demonstrate the effectiveness and robustness of the proposed controllers. Contrasting simulation results indicate that the neural network backstepping sliding mode controller reduces the chattering effectively and has better performance against the sliding mode controller.

Extremely large magnetoresistance in the “ordinary” metal ReO3

The extremely large magnetoresistance (XMR) observed in many topologically nontrivial and trivial semimetals has attracted much attention in relation to its underlying physical mechanism. In this paper, by combining the band structure and Fermi surface (FS) calculations with the Hall resistivity and de Haas-Van Alphen (dHvA) oscillation measurements, we studied the anisotropy of magnetoresistance (MR) of ReO$_3$ with a simple cubic structure, an "ordinary" nonmagnetic metal considered previously. We found that ReO$_3$ exhibits almost all the characteristics of XMR semimetals: the nearly quadratic field dependence of MR, a field-induced upturn in resistivity followed by a plateau at low temperatures, high mobilities of charge carriers. It was found that for magnetic field \emph{H} applied along the \emph{c} axis, the MR exhibits an unsaturated \emph{H}$^{1.75}$ dependence, which was argued to arise from the complete carrier compensation supported by the Hall resistivity measurements. For \emph{H} applied along the direction of 15$^\circ$ relative to the \emph{c} axis, an unsaturated \emph{H}$^{1.90}$ dependence of MR up to 9.43~$\times$~$10^3$$\%$ at 10~K and 9~T was observed, which was explained by the existence of electron open orbits extending along the $k_{x}$ direction. Two mechanisms responsible for XMR observed usually in the semimetals occur also in the simple metal ReO$_3$ due to its peculiar FS (two closed electron pockets and one open electron pocket), once again indicating that the details of FS topology are a key factor for the observed XMR in materials.

Detection and Analysis of Low-voltage Complete Reactive Power Compensation Device

Detection and Analysis of Low-voltage Complete Reactive Power Compensation Device

Analysis of an optical SDM ring network model for applying MIMO processing

Optical multiple-input multiple-output (MIMO) technology is introduced into optical space division multiplexing (SDM) communication as an effective solution for the crosstalk issue. Unfortunately, this application is limited because all the channel information over the transmission link must be transmitted to MIMO receivers for complete crosstalk compensation, which indicates difficulty in applying MIMO to the transmission path via optical switches. We newly propose that one of the solutions to this limitation is a ring network because all channel information can be maintained in the ring. In particular, a typical ring network model comprising optical add-drop multiplexers (OADMs) and multicore fibers (MCFs) is introduced, and the ability of MIMO to compensate for capacity degradation because of the inter-core crosstalk is investigated. Moreover, the protection function, which is essential for the ring network, is also evaluated under the fiber and fiber core failures. As per the simulation results, although the protection operation affects the transmission capacity, the capacity loss is suppressed in the event of a failure to < 5%. We believe that these results provide useful information for designing SDM-based optical networks.

An Integrated Compensation Method for the Force Disturbance of a Six-Axis Force Sensor in Complex Manufacturing Scenarios.

As one of the key components for active compliance control and human–robot collaboration, a six-axis force sensor is often used for a robot to obtain contact forces. However, a significant problem is the distortion between the contact forces and the data conveyed by the six-axis force sensor because of its zero drift, system error, and gravity of robot end-effector. To eliminate the above disturbances, an integrated compensation method is proposed, which uses a deep learning network and the least squares method to realize the zero-point prediction and tool load identification, respectively. After that, the proposed method can automatically complete compensation for the six-axis force sensor in complex manufacturing scenarios. Additionally, the experimental results demonstrate that the proposed method can provide effective and robust compensation for force disturbance and achieve high measurement accuracy.

Алгоритмы компенсации искажений сигналов при распространении по спутниковым ионосферным радиолиниям.

Methods for describing of digital signal complex envelope distortions due to influence of satellite ionosphere radiolines based on linear filtering methods are presented. Distortions of the phase-frequency characteristics of the digital signal envelopes due to the dispersion properties of the ionosphere cause time scattering and the occurrence of intersymbol interference, which reduce the reliability of communication. This determines the relevance of the development of the computational procedure for processing digital signals that reduce the effectiveness of this type of interferences. The descriptions of the algorithms for compensation of these distortions based on the use of the broadband pilot-signals and the formation of an inverse linear filter are given. A useful property of the considered pilot-signals is the coincidence of their structure (frequency band, envelope type, manipulation law) with the structure of information digital signals. By means of computer simulations of this algorithms, the possibility of almost complete compensation of the considered distortions of wideband signals is shown.

An augmented food strategy leads to complete energy compensation during a 15-day military training expedition in the cold.

Soldiers on military expeditions usually fail to compensate for the increase in energy expenditure, with potential deleterious consequences. We therefore analyzed the characteristics of energy compensation in 12 male soldiers, during a 15‐day expedition in the cold, while alleviating some of the contextual limitations of food intake (~20‐MJ daily bags of easy‐to‐use, highly palatable and familiar foods with multiple and long breaks allowed during the day). Body and fat mass losses were low and moderate, respectively (−1.13 ± 1.42% and −19.5 ± 15.6%, respectively, p < .021). Mean energy intake (EI) was high (~16.3 MJ) and increased at each third of the expedition (15.3 ± 2.1, 16.1 ± 2.1, and 17.6 ± 2.0 for D1–5, D6–10 and D11–15, respectively, p < .012). This resulted in reaching a neutral energy balance as soon as the D6 to 10 period and reaching normal energy availability during D11 to 15. Participants only increased their EI during the mid‐day (10:00–14:00) period (p = .002) whereas hunger and thirst only increased in the morning, with higher scores during D11–15 than D1–5 (p < .009). Last, the reward value of sweet foods was also higher during D11–15 than during D1–5 (p = .026). The changes in body mass were positively associated with EI (r = 0.598, p = .040) and carbohydrate intake (r = 0.622, p = .031). This study indicates that complete energy compensation can be reached in challenging field conditions when food intake is facilitated, offering some guidelines to limit energy deficit during operational missions.

Compensation for the Harm Caused by the Crime: Experience of Russia and the Cis Countries

The article examines the creation and functioning of specialized funds for the compensation of harm to victims of crime, as well as a comparative analysis of various methods of compensation for harm caused by a crime, provided for in the legislation of a number of CIS member states. In conclusion, it is pointed out that it is necessary to introduce into domestic law enforcement practice the successfully tested experience of compensation for harm from the legal systems of foreign states, which, in turn, creates the preconditions for the most complete and fair compensation for harm to victims of crimes, and the imposition of material responsibility on those responsible for committing criminal offenses.

Research on Fengjiashan Reservoir Ecological Compensation Mechanism Based on Ecosystem Service Function

The impact of hydropower projects on the ecosystem is dynamic and complex. Constructing a complete ecological compensation mechanism can ensure the effective progress of ecological compensation. The ecosystem service value of the Fengjiashan Reservoir such as water supply, fish farming, hydropower, water regulation, water resources accumulation, biodiversity, and environmental purification, is calculated with market value method, alternative engineering method and other evaluation methods, and the ecological compensation mechanism of the reservoir is studied. The results show that the value of its ecosystem services is 230,912,700 yuan, and the amount of ecological compensation determined on the basis of ecosystem service functions is 101,866,200 yuan. The main sources of compensation funds are taxes, water surcharges and government financial subsidies.

MTF improvement for optical synthetic aperture system via mid-frequency compensation.

Optical synthetic aperture imaging system has grown out the quest for higher angular resolution in astronomy, which combines the radiation from several small sub-apertures to obtain a resolution equivalent to that of a single filled aperture. Due to the discrete distribution of the sub-apertures, pupil function is no longer a connected domain, which further leads to the attenuation or loss of the mid-frequency modulation transfer function (MTF). The mid-frequency MTF compensation is therefore a key focus. In this paper, a complete mid-frequency compensation algorithm is proposed, which can extract and fuse the frequency of different synthetic aperture systems and monolithic aperture systems according to their special MTF characteristics. The dimensions of the monolithic aperture and optical synthetic aperture system are derived, and the longest baseline of the monolithic aperture is much smaller than that of the optical synthetic aperture system. Then the separated spatial frequency information is extracted and synthesized according to the spatial frequency equivalence point. Finally, the full-frequency enhanced image is recovered by using improved Wiener-Helstrom filter, which adopts specific parameters based on different sub-aperture arrangements. The mid-frequency MTF of Golay-3 increases from 0.12 to 0.16 and that of Golay-6 increases from 0.06 to 0.18. Both the simulation and experiment prove that the proposed method not only realizes the spatial resolution determined by the longest baseline of the optical synthetic aperture system, but also successfully compensates its mid-frequency MTF.

Evolution of dosage compensation does not depend on genomic background.

Organisms have evolved various mechanisms to cope with the differences in the gene copy numbers between sexes caused by degeneration of Y and W sex chromosomes. Complete dosage compensation or at least expression balance between sexes has been reported predominantly in XX/XY systems, but rarely in ZZ/ZW systems. However, this often-reported pattern is based on comparisons of lineages where sex chromosomes evolved from nonhomologous genomic regions, potentially differing in sensitivity to differences in gene copy numbers. Here we document that two reptilian lineages (XX/XY iguanas and ZZ/ZW softshell turtles), which independently co-opted the same ancestral genomic region for the function of sex chromosomes, evolved different gene dose regulatory mechanisms. The independent co-option of the same genomic region for the role of sex chromosomes as in the iguanas and the softshell turtles offers great opportunity for testing evolutionary scenarios on sex chromosome evolution under the explicit control of the genomic background and gene identity. We show that the parallel loss of functional genes from the Y chromosome of the green anole and the W chromosome of the Florida softshell turtle led to different dosage compensation mechanisms. Our approach controlling for genetic background thus does not support that the variability in the regulation of gene dose differences is a consequence of ancestral autosomal gene content.

Digital system for frequency regulation and stabilisation of a four-frequency Zeeman laser gyroscope

We report the results of theoretical and experimental studies of a digital system for regulating and stabilising the frequency of a four-frequency Zeeman laser gyroscope (ZLG), in which generation occurs simultaneously on two longitudinal modes with orthogonal circular polarisations; therefore, four light waves propagate in the optical ring resonator. In contrast to a two-frequency Zeeman laser gyroscope, a four-frequency ZLG does not use the intensity modulation signal of one of the light waves, which appears when an alternating magnetic field is applied to the active medium, to analyse the frequency detuning of longitudinal modes from the centre of the active-medium gain contour. At the same time, it is possible to construct a digital perimeter adjustment system (PAS), which allows the resonator perimeter to be adjusted so that the magnetic components of the zero drift of the gyroscope for two longitudinal generation modes are equal and opposite in sign. Due to this, almost complete compensation for the magnetic component of the zero drift of the gyroscope is realised in a four-frequency ZLG. The use of the digital system makes it possible to provide a higher accuracy of the resonator perimeter adjustment than that in a two-frequency ZLG, even with a relatively small bit capacity of the PAS digital-to-analogue conversion (DAC), and to fully take advantage of the capabilities of a four-frequency ZLG to reduce the magnetic sensitivity.

Do aquatic ectotherms perform better under hypoxia after warm acclimation?

Aquatic animals increasingly encounter environmental hypoxia due to climate-related warming and/or eutrophication. Although acute warming typically reduces performance under hypoxia, the ability of organisms to modulate hypoxic performance via thermal acclimation is less understood. Here, we review the literature and ask whether hypoxic performance of aquatic ectotherms improves following warm acclimation. Interpretation of thermal acclimation effects is limited by reliance on data from experiments that are not designed to directly test for beneficial or detrimental effects on hypoxic performance. Most studies have tested hypoxic responses exclusively at test temperatures matching organisms' acclimation temperatures, precluding the possibility of distinguishing between acclimation and acute thermal effects. Only a few studies have applied appropriate methodology to identify beneficial thermal acclimation effects on hypoxic performance, i.e. acclimation to different temperatures prior to determining hypoxic responses at standardised test temperatures. These studies reveal that acute warming predominantly impairs hypoxic performance, whereas warm acclimation tends to be either beneficial or have no effect. If this generalises, we predict that warm-acclimated individuals in some species should outperform non-acclimated individuals under hypoxia. However, acclimation seems to only partially offset acute warming effects; therefore, aquatic ectotherms will probably display overall reduced hypoxic performance in the long term. Drawing on the appropriate methodology, future studies can quantify the ability of organisms to modulate hypoxic performance via (reversible) thermal acclimation and unravel the underlying mechanisms. Testing whether developmental acclimation and multigenerational effects allow for a more complete compensation is essential to allow us to predict species' resilience to chronically warmer, hypoxic environments.

Performance of a PEM fuel cell with oscillating air flow velocity: A modeling study based on cell impedance

A model of PEM fuel cell impedance is developed taking into account imposed harmonic perturbation of the air flow velocity in the cathode channel. The flow velocity modulation with the amplitude proportional to AC amplitude of the cell potential lowers the resistivity Rh due to oxygen transport in channel. When relative amplitudes of velocity and potential oscillations are equal, a complete compensation of Rh occurs. This effect explains experimental findings of Kim et al. (https://doi.org/10.1016/j.jpowsour.2008.06.069) and Hwang et al. (https://doi.org/10.1016/j.ijhydene.2010.01.064), who demonstrated significant improvement of PEM fuel cell performance under oscillating air flow velocity.

Comments on “Do Ultrafine Cloud Condensation Nuclei Invigorate Deep Convection?”

AbstractHere we elaborate on the deficiencies associated with the theoretical arguments and model simulations in a paper by Grabowski and Morrison (2020, hereafter GM20) that argued convective invigoration by aerosols does not exist. We show that the invigoration can be supported by both accurate theoretical analysis and explicit physics modeling with prognostic supersaturation and aerosols. Negligible invigoration by aerosols via drop freezing in GM20 was explained by a complete compensation between the heating effect from the freezing of extra liquid water and the extra loading effect during droplet ascending. But the reality is that droplet ascending then freezing occur at different locations and time scales, producing complex nonlinear responses that depend on the duration and location of the forcing. Also, this argument neglects the effect of off-loading of precipitating ice particles, increases in condensation during ascending, and riming and deposition accompanying droplet freezing. Regarding the warm-phase invigoration, the quasi-steady assumption for supersaturation as adopted in GM20 makes condensation independent of droplet number and size, therefore an incorrect interpretation of warm-phase invigoration. We illustrate that the quasi-steady assumption is invalid for updrafts of deep convective clouds in clean conditions because of the high acceleration of vertical velocity and the fast depletion of droplets by raindrop formation and accretion. Any assumption imposed on supersaturation, such as quasi-steady approximation and saturation adjustment, leads to errors in the evaluation of aerosol effects on diffusional growth and related buoyancy. Furthermore, we demonstrate that the piggybacking approach they used cannot prove or disprove the convective invigoration.

Система прямого керування струмом активного фільтра

The main direction of research is the optimization of the active filter, simplification of the control system and the identification of new algorithms for calculating the compensating currents. There has been improved the direct current control system of active filter with the formation of sinusoidal signals equal to the fundamental harmonic of phase load currents, as well as non-sinusoidal asymmetric signals, as the difference between input phase currents of load and fundamental harmonics, to filter higher harmonics and balancing currents filtering of higher harmonics and balancing of nonlinear asymmetric loads. The control system, which consists of two units: the unit for generating the current compensation of higher harmonics and the unit for converting currents from the phase coordinate system to the coordinate system of instantaneous symmetrical components, provides almost complete compensation for linear and nonlinear distortion. In the case of using one unit for converting currents from the phase coordinate system to the coordinate system of instantaneous symmetrical components, which significantly simplifies the implementation of the control system, provides sufficient for mass consumers quality compensation of higher harmonics (provides compensation of the third, fifth, seventh and ninth current harmonics , and the level of uncompensated higher harmonics is determined by the eleventh and thirteenth harmonics, the content of which is significantly lower) and full load balancing. It is shown that the system of direct current control of the active filter in the case of using the vector of phase currents and the vector of phase voltages can be used for full compensation of reactive power. In this case, there is a slight initial overregulation of the reactive power, which is automatically compensated. The reactive power is regulated indirectly by the voltage support circuit on the capacitor of the active filter voltage inverter.

The evolution of sex chromosome dosage compensation in animals

The evolution of heteromorphic sex chromosomes shall lead to gene expression dosage problems, as in at least one of the sexes, the sex-linked gene dose has been reduced by half. It has been proposed that the transcriptional output of the whole X or Z chromosome should be doubled for complete dosage compensation in heterogametic sex. However, owing to the variability of the existing methods to determine the transcriptional differences between sex chromosomes and autosomes (S:A ratios) in different studies, we collected more than 500 public RNA-Seq data set from multiple tissues and species in major clades and proposed a unified computational framework for unbiased and comparable measurement of the S:A ratios of multiple species. We also tested the evolution of dosage compensation more directly by assessing changes in the expression levels of the current sex-linked genes relative to those of the ancestral sex-linked genes. We found that in mammals and birds, the S:A ratio is approximately 0.5, whereas in insects, fishes, and flatworms, the S:A ratio is approximately 1.0. Further analysis showed that the fraction of dosage-sensitive housekeeping genes on the X/Z chromosome is significantly correlated with the S:A ratio. In addition, the degree of degeneration of the Y chromosome may be responsible for the change in the S:A ratio in mammals without a dosage compensation mechanism. Our observations offer unequivocal support for the sex chromosome insensitivity hypothesis in animals and suggest that dosage sensitivity states of sex chromosomes are a major factor underlying different evolutionary strategies of dosage compensation.