Saturation Phenomenon Research Articles

Evaluating the saturation effect of vegetation indices in forests using 3D radiative transfer simulations and satellite observations

Vegetation indices (VIs) have been used extensively for qualitative and quantitative remote sensing monitoring of vegetation vigor and growth dynamics. However, the saturation phenomenon of VIs (i.e., insignificant change at moderate to high vegetation densities) poses a known limitation to their ability to characterize surface vegetation over the dense canopy. Although the mechanisms underlying saturation are relatively straightforward and several VIs have been proposed to mitigate the saturation effect, the assessment of the saturation effect of VIs remains insufficient. Notably, no unified metric has been proposed to quantify the VI saturation phenomenon, limiting VI selection in practical applications. In this study, we proposed two indicators to describe the saturation phenomenon and utilized a well-validated three-dimensional (3D) canopy radiative transfer (RT) model large-scale remote sensing data and image simulation framework (LESS) to simulate the bidirectional reflectance factor (BRF) of six forests scenes and assessed the variations in VIs in relation to leaf area index (LAI) values over different backgrounds, sun-sensor geometries, and spatial distribution types. The saturation characteristics of 36 VIs were evaluated in combination with simulation results and satellite observations from multiple sensors. The ranking of VI saturation from simulated and satellite results revealed a good agreement. Our results indicated that the simple ratio vegetation index (SR) performed best with the highest saturation point and can well characterize the surface vegetation condition until LAI reaches 4. Besides, we found that the saturation effect of VIs was influenced by soil brightness, sun-sensor geometry, and canopy structure. SR, modified simple ratio (MSR) and normalized green red difference index (NGRDI) were the most susceptible to these disturbing factors, although they had higher resistance to saturation. Modified triangular vegetation index 1 (MTVI1), modified non-linear vegetation index (MNLI), triangular greenness index (TGI), and triangular vegetation index (TriVI) performed well overall, combining the ability to resist saturation and disturbance factors. Appropriate application of VIs can help better understand vegetation responses to climate change and accurately assess ecosystem status. Our results contribute to the understanding of the VI saturation effect and provide a combined model and satellite data experimental workflow in appropriate VI selection to accurately characterize vegetation.

Method for the identification of 60Co in an industrial gamma irradiator

This study presents a method for the identification of a set of radioactive sources of 60Co, in an industrial irradiator. This identification was requested by a Mexican regulatory authority. To fulfill this request, a method was developed to make the identification by the gamma spectrometry method. The complexity in the measurement lies in the fact that the set of sources has an activity of 500,000 Ci of 60Co and the identification is complicated because with that gamma intensity one has to have a strategy to reduce the phenomena of saturation, pile up and dead time and achieve that photopeaks generated in the gamma spectrum of the gamma energies of 60Co are clearly visible. A low efficiency and relatively high resolution CZTe detector, was selected, which was placed in an acrylic box with a collimated lead shield to carry out the measurement inside the irradiator pool to reduce scattered radiation and to be able to clearly appreciate the spectrum gamma of 60Co.

Design of Rotor Magnetic Barrier Structure of Built-in Permanent Magnet Motor Based on Taguchi Method

In this paper, a 20kW vehicle built-in permanent magnet synchronous motor is taken as an example, and a magnetic barrier structure is added to the rotor of the motor to solve the uneven saturation problem of the rotor side magnetic bridge. This structure improves the air-gap flux density waveform of the motor by influencing the internal magnetic flux path of the motor rotor, thus improving the sine of the no-load back EMF waveform of the motor and reducing the torque ripple of the motor. At the same time, Taguchi method is used to optimize the structural parameters of the added magnetic barrier. In order to facilitate the analysis of its uneven saturation phenomenon and improve the optimization effect, a simple equivalent magnetic network (EMN) model considering the uneven saturation of rotor magnetic bridge is established in this paper, and the initial values of optimization factors are selected based on this model. Finally, the no-load back EMF waveform distortion rate, torque ripple and output torque of the optimized motor are compared and analyzed, and the influence of magnetic barrier structure parameters on the electromagnetic performance of the motor is also analyzed. The results show that the optimized motor can not change the output torque of the motor as much as possible on the basis of reducing the waveform distortion rate of no-load back EMF and torque ripple.

Coupled Hybrid Stochastic Resonance With Multiobjective Optimization for Machinery Dynamic Signature and Fault Diagnosis

Most traditional stochastic resonance methods pose three fundamental limitations in extracting fault signature: (1) simulated impulse signals are insufficient to match the complicated mechanical vibration signals; (2) one-dimensional signals are vulnerable to interference from multiscale noise, which potentially yields false detection; and (3) optimization function in the signal-to-noise ratio largely depends on the advanced requirements of the characteristic frequency, thereby restricting the development for actual operation. Accordingly, this study investigated the dynamic model of rolling bearings and explored the benefits of the coupled hybrid stochastic resonance (CHSR) method for identifying weak signal signatures. In addition, we proposed multi-objective optimization and established a dynamic model of a rolling bearing with four degrees of freedom under a rotor system with external excitation. Overall, the proposed system offers three main advantages: (1) the dynamic model facilitates correspondence with real vibration signals; (2) the CHSR method can process two-dimensional signals and overcome the saturation phenomenon, which enhances the weak useful signal signature describing machinery health; and (3) the cross-correlation spectral kurtosis and the critical amplitude are defined within the multi-objective function to adaptively optimize the parameter adjustment of the CHSR. Thereafter, the proposed method exhibited adequate enhancement ability integrated the study on dynamic simulation and machinery bearings of wind power generator. Moreover, the applied machine learning model further clarified the superior performance of CHSR method in identifying the weak fault signature.

Il nome di dio, tra metafisica, fenomenologia e teologia. La prospettiva di Jean-Luc Marion e l’influsso di Edmund Husserl

This article presents the evaluation that Marion makes of the onto- theological determination of metaphysics and of conceptual idolatry, and the resolution that is proposed through the phenomenology of the gift. The new name of God, in the logic of this phenomenology of Marion, no longer starts from the language of being, esse, but from gift and love. “Love purifies our heart from every idol, since it alone is given and said as the name of God and yet it alone occurs in the experience of this world”. God is a Gift, is donation; he is Love, and his revelation is the saturated phenomenon par excellence which shows the impossibility of impossibility by God. In past times the dialogue of theology with other sciences and atheists was partly supported by arguments provided by classical metaphysics. The cry of triumph of nihilism calls for the very end of this metaphysics and the death of its God (Nietzsche). By what name, then, do we call God after “the death of God”, in today’s philosophical background? Also, if God is really God, how can he die? Only a God who is only a “god” can die. If metaphysics has come to its end, who will assume his task and duty? These are some questions which, following Marion’s and Husserl’s indications, we will briefly try to answer, after a short presentation of the status quaestionis.

Simple one-parameter function to retrieve the correct exposure value from CR-39 radon detectors in high-saturation regime. Checks on two kinds of analysis systems.

Radon activity concentration measurements in air can be easily performed by using CR-39 detectors whose response is almost linear in the range of medium-low exposures. However, when the exposure values grow too much, a saturation phenomenon becomes relevant and some corrections have to be adopted even if they cannot always be very accurate and easy to apply. Therefore, a simple alternative method for determining the correct response curve of the CR-39 detectors, from low up to very high radon exposures, is showed. To verify its robustness and the general applicability, several certified measurements were carried out in a radon chamber at different levels of exposure. Moreover, two different types of commercially available radon analysis systems were used.

Experimental investigation of the direct and subharmonic responses of a new design of centrifugal pendulum vibration absorber

Centrifugal pendulum vibration absorbers (CPVAs) are often used by the automotive industry to reduce vibrations of the drivetrain. These passive devices consist of several masses oscillating along a given path relative to a rotor. Recent CPVA systems make use of rocking pendulums, meaning that the pendulums rotate about their centre of mass during their motion along their path. In this work, measurements on a new CPVA architecture made of ball-type rocking pendulums are performed in classical and subharmonic operations. To the authors’ knowledge, they lead to the first comparisons between experimental and analytical results regarding the nonlinear detuning of the rotor’s antiresonance and the saturation of the rotor’s response. It is also the first time this saturation phenomenon is observed experimentally. The CPVA investigated is shown to have a high filtering efficiency but its pendulums are subjected to slipping, which limits the operating range of the system. Experimental and analytical investigations of the slipping are carried-out to estimate the limit of adherence of the system.

Enhanced multi-state estimation methods for lithium-ion batteries considering temperature uncertainties

Due to their high energy density and minimal emissions, lithium-ion batteries are frequently employed in electric vehicles (EVs). Accurate estimation of the micro-parameters, state of charge (SOC), and state of health (SOH) are a few primary monitoring functions of the battery management system (BMS) to increase the battery's efficiency and safety under various operating conditions. This paper proposes a SOC and SOH co-estimation method by adopting an ensemble empirical mode decomposition method with adaptive noise and an autoencoder (EEMDA) to extract, decompose, and reconstruct the full-scale charging voltage and current data for a dual extended Kalman filter (DEKF) with multi-parameter and time-scale updates for accurate estimation based on a variable forgetting factor limited memory recursive least squares (VFF-LMRLS) method. The VFF-LMRLS method is used to solve the data saturation phenomenon and identify the battery's characteristic micro-parameters based on a proposed dynamic migration second-order resistor-capacitor equivalent circuit model under different operating states. Battery tests are conducted at temperatures ranging from −10 to 50 °C under complex working conditions. Using the VFF-LMRLS method, the effects of different temperatures on the micro-parameters are discussed. The SOC and SOH results of the proposed EEMDA-DEKF method based on the dynamic migration battery model show that the mean absolute error and root mean square error metrics have the least values of 0.0233% and 0.0252%, which signify an optimal performance improvement of 93.26% and 93.66%, respectively, compared to the conventional DEKF method. Based on the experimental results and analyses, the proposed method has a high degree of accuracy and robustness, which makes it feasible for battery monitoring and prognostic BMS applications.

자기저항 동기 전동기에서 자속 포화 모델의 상호 포화항에 대한 매개변수 추정

This study proposes a parameter estimation method for cross saturation term of flux saturation model including cross saturation of synchronous reluctance motor(SynRM). SynRM exhibits large cross saturation and self-saturation. A flux saturation model including the cross saturation term has been proposed to represent the cross saturation. This model satisfies the reciprocity condition, which represents a nonlinear saturation phenomenon well. It also includes a self-saturation term and a cross saturation term. The self-saturation term includes an arctangent function, and the cross saturation term includes a logarithm function and a fraction function. The parameter estimation method for the self-saturation term has been developed, but the parameter estimation method for the cross saturation term has not been presented yet. In this study, considering the role of each parameter in the cross saturation term, the parameters included in the log function are first selected. Then, the remaining parameters are estimated using the linear least squares method. The proposed parameter estimation method is verified for SynRM of 1.5 kW.

Analysis of characteristics of rail transit stray current and saturation mechanism of current transformer

Abstract The DC bias may affect the transient transfer characteristics of the current transformer (CT), threatening the correct action of the relay protection and the safe operation of the power system. Compared with the high voltage direct current (HVDC) transmission in the unipolar-earth loop operation mode and geomagnetically induced current (GIC), the amplitude of the stray current is smaller, and the randomness and fluctuation are larger and accompanied by sudden changes. Combining the characteristics of stray current and the CT equivalent model considering the eddy current loss of the iron core, the mechanism of local transient saturation under the influence of bias magnetization is explained, and the CT saturation phenomenon caused by stray current and its effect on line distance protection are simulated and analyzed. The research shows that the influence of low amplitude and high duration of stray current will make the magnetic flux of CT grow and affect the transmission of steady-state and transient-state so that the measurement impedance appears amplitude-phase shift, which leads to under-range rejection of distance protection.

Mapping Growing Stem Volume Using Dual-Polarization GaoFen-3 SAR Images in Evergreen Coniferous Forests

Unaffected by cloud cover and solar illumination, synthetic aperture radar (SAR) images have great capability to map forest growing stem volume (GSV) in complex biophysical environments. Up to now, c-band dual-polarization Gaofen-3 (GF-3) SAR images, acquired by the first Chinese civilian satellite equipped with multi-polarized modes, are rarely applied in mapping forest GSV. To evaluate the capability of dual-polarization GF-3 SAR images in mapping forest GSV, several proposed derived features were initially extracted by mathematical operations and applied to obtain optimal feature sets by different feature sorting methods and feature selection methods. Then, the maps of GSV in an evergreen coniferous forest were inverted by various machine learning algorithms and stacking ensemble learning methods with different strategies. The results implied that backscattering coefficients and partially proposed derived features showed high sensitivity to the forest GSV, and the saturation phenomenon also obviously occurred once the forest GSV was larger than 300 m3/ha. Furthermore, the results showed that the accuracy of the mapped GSV was significantly improved using the stacking ensemble learning methods. Using various optimal feature sets and base models (MLR, KNN, SVM, and RF), the rRMSE values mainly ranged from 30% to 40%. After using the stacking ensemble learning methods, the values of rRMSE ranged from 16.71% to 20.51%. This confirmed that dual-polarization GF-3 images have great potential to map forest GSV in evergreen coniferous forests.

The Saturated Phenomenon of Flesh and Mineness and Otherness of the Body in Illness

A key topic within the field of the phenomenology of medicine has been the relationship between body and self in illness, including discussions about the otherness and mineness of the body. The aim of this article is to distinguish between different meanings of bodily otherness and mineness in illness with reference to the interpretation of the body as "saturated phenomenon," inspired by the phenomenology of Jean-Luc Marion. With the help of Marion's ideas it is possible to distinguish between two meanings of bodily otherness and of mineness (objective and non-objective forms). These distinctions support and elaborate on ideas already found in the phenomenology of medicine and offer further insights into the nature of the experience of illness.

Sequential Solid-Phase Microextraction with Biocompatible Coating Materials to Address Displacement Effects in the Quantitative Analysis

Solid-phase microextraction (SPME) is a simple and effective sample-preparation technique for the analysis of complex samples. However, sample matrices containing high concentrations of nonpolar substances or spiked analytes in free form can cause swelling, saturation, and/or competition phenomena in the coating material. This results in a displacement effect wherein polar analytes with low affinities for the solid coating material are displaced by nonpolar substances in the matrix or spiked analytes with a high affinity. Therefore, the quantitative analysis of polar analytes can be challenging, as the displacement effect causes non-linearity in the calibration curves. This paper presents a comprehensive investigation of the conditions under which the displacement effect occurs and how it influences the quantitative analysis of polar analytes. To remedy this issue, a sequential SPME strategy using two SPME blades with different selectivities is applied. SPME blades offer a large surface area and coating volume─and thus, greater extraction capacity─which may mitigate the displacement effect. In addition, the biocompatible coatings on the SPME blades are comprised of small amounts of sorbent particles embedded by a polyacrylonitrile (PAN) binder, which allows them to be directly immersed into complex matrixes such as biological and food samples, as the PAN acts as a barrier that prevents the adsorption of large macromolecules (e.g., cells and proteins). As such, a C18/PAN-coated blade was applied for the first extraction step, which significantly decreased the concentrations of nonpolar compounds in the sample. In the second step, a hydrophilic-lipophilic balanced (HLB)/PAN-coated blade was employed to extract the polar analytes and any remaining nonpolar analytes. The proposed sequential SPME strategy successfully enabled the quantitative determination of polar and nonpolar drugs of abuse with log P values ranging from 0.16 to 4.98 in biological matrices while also providing good linearities.

An experimental study of the saturated impulse for metal plates under slamming

Engineering structures can suffer severe local structural damage when subjected to extreme dynamic pulse loadings such as slamming impact. However, there is paucity of information on how the loading pulses affect the large plastic deformations. This paper presents information on an experimental investigation into the dynamic pressure pulse generated by slamming and the plastic response of metal plate. In our experiments, plates made of aluminum and steel alloy, were dropped from various heights ranging from 0.1 m to 1.3 m, onto the calm water in a tank. Based on the experimental results, the effects of structural material and water impact velocity on the slamming pressures pulse are investigated in detail. The results indicate that not only the peak pressure but also the pressure pulse duration play important roles in governing the dynamic response of the impacted structures. It is shown that the maximum strain and deflection at the plate center increase almost linearly with the drop height of the drop model. In view of the lack of previous experimental evidence for the saturation phenomenon of structures under slamming, we compared the dynamic response at the center of the plate with the experimentally measured slamming pressure under various drop heights, so that we have evidently verified the saturation phenomenon of flat plates for the first time under slamming in drop tests. It is also revealed that the dynamic response of the flat plates under slamming becomes more prone to the saturation phenomenon with the increase of drop height.

Vector meson photoproduction in UPCs with FoCal

We discuss the physics prospects of photon-induced measurements using the high-granularity FoCal detector to be installed at the ALICE experiment, covering the pseudorapidity interval 3.4 ≤ η ≤ 5.8. This new detector, scheduled to be in operation from Run 4, will explore the small Bjorken-x physics region in an unprecedented way. In this region the gluon ,saturation phenomenon is expected to be dominant. Combined with the rest of the ALICE subdetectors, including the zero degree calorimenters, FoCal will serve to reconstruct in a model-independent way the measured photoproduction cross sections for vectors mesons in a wide range of photon-target energies, down to x values of about 7 × 10−6 and 2 × 10−6 in ultra-peripheral photon–proton and photon–lead collisions, respectively.

Research on performance of ionization chamber used in medical laser proton accelerator based on Garfield++

Gas ionization chamber has the advantage of accurate and reliable measurement data, which is widely used in beam current monitoring of proton and heavy ion beam therapy systems. According to the characteristics of the proton beam signal of the laser accelerator, because of its ultra-high peak current intensity, the peak current intensity of the beam generated by the traditional accelerator is much higher than that of the traditional accelerator. The gas ionization chamber cannot measure the proton beam with this characteristic, and the incident laser proton beam is likely to cause signal saturation and distortion in the gas ionization chamber. Therefore, it is necessary to improve the physical design of the gas ionization chamber and the supporting electronic system to improve the detection technology of the gas ionization chamber dedicated to the ion beam generated by the laser acceleration. In this paper, the physical design of the gas ionization chamber is optimized to avoid signal saturation in the gas ionization chamber while measuring the laser proton beam signal. With the method of modeling and simulation analysis of the gas ionization chamber based on the Garfield++, the optimal value is given in three aspects: the type selection of the gas medium, the gas pressure setting and the setting of the voltage of the gas ionization chamber in order to optimize the measurement signal saturation phenomenon caused by the large transient beam current intensity, and bring theoretical basis and guiding significance to the actual experimental operation. The research concludes that when helium is selected as the gas medium of the gas ionization chamber, the signal saturation can be effectively reduced; when the integration time of the electronic system of the gas ionization chamber is 500 ns, and the current measurement range is ±16 μA in actual, the optimized gas pressure should be set lower than 540 Torr and the voltage value lower than 300 V to match the electronic measuring range of the gas ionization chamber while detecting the current signal; when the signal detected is the integrated charge, the voltage setting of the gas ionization chamber has nearly nothing to do with the signal collected, but to adjust the gas pressure in the gas ionization chamber to optimize the final data.

Transformation of carrier recombination mechanism as increasing the Germanium content in Cu2ZnGexSn1-xS4 single crystal prepared by molten salt method

Return to the physics origin of Cu2ZnSnS4 type (CZTS-type, include CZGS, CZGTS, CZTSSe, etc.) material system, studying the influence of replacement elements on the optoelectronic properties by preparing high-quality single crystal materials to clarify the relationship between the key defect states of materials and carrier dynamics is the only way which must be passed to find efficient paths to improve the existing performance of CZTS-type optoelectronic devices. Herein, the optical behavior of high-quality Cu2ZnGexSn1-xS4 (CZGTS) single crystal prepared by the molten salt method and its relationship with Ge content were systematically studied using a photoluminescence (PL) and absorption tests at room temperature. Combined with the simple electrical tests, the transformation of carrier recombination mechanism as increasing the Germanium content in CZGTS single crystal before and after phase transition were reported for the first time. The transmission electron microscopy images, X-ray diffraction spectra and Raman scattering spectra of CZGTS were adopted to reveal the evolution mechanism of single crystal growth and phase transition caused by the change of Ge composition. The results show that the tunable blue-shift of PL peak emerges with the increase of Ge content and the excitation power dependence has a saturation phenomenon in the CZGTS single crystal particles. In consideration of the optical bandgap, PL peak position, PL intensity, carrier lifetime and the macroscopic resistivity, it is confirmed that the intrinsic PL behavior could be effectively tailored by different Ge amounts. Compared with the recombination PL of interband carrier (Ep > Eg) in Cu2ZnSnS4, the band tailed carriers (Ep < Eg) dominated by defect states would play a powerful role in CZGTS single crystal. Our work provides a strategy for tailoring the bandgap of CZGTS materials and a new perspective for understanding the influence of defect states on carrier dynamics.

A Simple DC-Offset Eliminating Method of the Series-Inductance Current for the DAB DC–DC Converter

Based on the phase-shift modulation, the dual-active-bridge (DAB) dc–dc converter always features the natural self-volt-second balance performance even during the transient process. Besides, different phase-shift ratios usually result in different initial series-inductance currents. Therefore, when the phase-shift ratio is suddenly changed for dealing with the change of required transferred power, a dc offset in the series-inductance current will emerge. Especially for the high-power condition, this dc offset lasts for a long time because of the high-current value but low damping conduction resistor. Then, the magnetic saturation phenomenon may emerge in the transformer, resulting in the potential failure of the converter system. To address this issue, a simple dc-offset eliminating method is proposed for the DAB dc–dc converter. Different from most of the existing methods, the proposed one is independent from the phase-shift modulation method. Therefore, the proposed dc-offset eliminating method can be easily embedded in different phase-shift modulation methods, such as single-phase-shift, double-phase-shift, and triple-phase-shift methods. Finally, the experimental results are provided to verify the effectiveness of the proposed dc-offset eliminating method for the DAB dc–dc converter.

Parameter optimisation of miniaturised SERF magnetometer below relaxation rate saturation region

The miniaturised spin-exchange relaxation-free (SERF) magnetometer has promising applications in biomagnetic measurements owing to its ultrasensitive magnetic field measurement capacity. In this paper, we propose a single-beam parameter-optimised SERF magnetometer that operates below the relaxation rate saturation region. Based on the relaxation rate model under zero-field resonance, the relationship between the magnetometer optimal working point and multiphysical parameters, including the optical power density, cell temperature, and nitrogen density, was studied. The experimental results verified the accuracy of the law deduced from the model. By adjusting the parameters according to our experimental results, a sensitivity of 17 fT/Hz1/2 (@31.5Hz) and bandwidth of 110 Hz were obtained optimally in a 5.5 cm3 magnetometer. The superiority of the optimised parameters in the miniaturised SERF magnetometer is verified. We found that the relaxation rate saturation region results from light absorption saturation, which leads to a performance decline of the SERF magnetometer. This relaxation rate saturation phenomenon widely exists in miniaturised SERF magnetometers, and the study of this phenomenon is helpful for further applications in arrayed integration of biomagnetic measurement.

Adaptive Feedback Linearization Control of SynRM Drives With On-Line Inductance Estimation

This article proposes an adaptive input-output Feedback Linearization Control ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLC</i> ) techniques for Synchronous Reluctance Motor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SynRM</i> ) drives, taking into consideration the iron losses. As a main original content, this work proposes a control law based on a new dynamic model of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SynRM</i> including iron losses as well as the on-line estimation of the static inductances. The on-line estimation of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SynRM</i> static inductances permits to inherently take into consideration the magnetic saturation phenomena occuring on both axes. As a major result, it permits a null stator current steady state tracking error even with a proportional derivative controller. The estimation law is obtained thanks to a Lyapunov-based analysis and thus the stability of the entire control system, including the estimation algorithm, is intrinsically guaranteed. The proposed adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLC</i> technique, has been tested experimentally on a suitably developed test set-up, and compared experimentally with its non-adaptive versions in both tuned and detuned working conditions. Moreover, a sensitivity analysis of the performance of the adaptive <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FLC</i> to the variations of the stator resistance at low speed has been made. Finally, an analysis of the effects of the iron losses on the control performance and stability at high speed in the field weakening region at medium/high loads has been made.