fluctuation rate
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2022 ◽  
Vol 2160 (1) ◽  
pp. 012080
Author(s):  
Kaijie Zhao ◽  
Sheng Zeng ◽  
Liangliang Zhao

Abstract When the enameled wire is winded onto the poles of the motor stator or rotor, the winding quality hugely relies on the control precision of the tension. Therefore, it is necessary to control the tension of the enameled wire in winding process. A tension control system is built with single chip microcomputer, the encoder and the servo motor. The PID feedback controller and feedforward controller are combined to form feedforward feedback controller, which using feedback information of swing angle deviation and feedforward information of wire frame position to adjust the pay off speed dynamically and control tension of enameled wire further. A procedural experimental modelling method is discussed in order to identify the feedforward model. The experiment is performed, it is found that in the typical situation of setting tension 1500 g, the tension fluctuation rate of the PID controller with feedforward model is only 2%, which is far better than that of pure PID controller with a fluctuation rate of 14%. The result shows that the proposed experimental modelling method hosts the characteristics of good accuracy, universality and applicability.


2021 ◽  
Vol 923 (2) ◽  
pp. 259
Author(s):  
Z. Wang ◽  
Z. G. Wen ◽  
J. P. Yuan ◽  
N. Wang ◽  
J. L. Chen ◽  
...  

Abstract We have carried out a detailed study of single-pulse emission from the pulsar J2048−1616 (B2045−16), observed at 732, 1369, and 3100 MHz frequencies using the Parkes 64 m radio telescope. The pulsar possesses three well-resolved emission components, with the central component resembling core emission. The single pulses show the presence of two distinct periodic modulations using fluctuation spectral analysis. About 12% nulls are found to create alternating bunches of nulls and bursts in a quasiperiodic manner with longer periodicities of 83, 28, and 14 rotational periods for simultaneous observations at 732 and 3100 MHz. At 1369 MHz, the quasiperiodic nulling is detected, as well, to modulate across the entire profile both in the core and conal components simultaneously with a fluctuation rate of about 50 rotational periods, and the nulling fraction is estimated to be around 10%. Additionally, the quasiperiodic modulations are significantly dependent on time. In addition to nulling, the pulsar also presents subpulse drifting in the single-pulse sequences with shorter periodicity. The subpulse drifting is presented in the conal components and is absent in the central core emission. The leading component is modulated in longitude with a period of three pulses. The trailing component remains phase stationary within the pulse window but periodically modulates in amplitude with a period of three pulses. Finally, possible physical mechanisms are discussed.


2021 ◽  
Vol 9 ◽  
Author(s):  
Yang Si ◽  
Linrui Ma ◽  
Laijun Chen ◽  
Hengrui Ma ◽  
Shengwei Mei

Aiming at the reliable grid connection of photovoltaic (PV) systems in frigid plateau regions, this work first designs a flexible hot dry rock (HDR) hybrid power system (HPS), making full use of the potential of HDR for energy storage and power generation. Based on the operation of HPS, a comprehensive energy system credible capacity assessment method considering the overall economy of the system and the reliability of the grid is established. In this method, the power allowable fluctuation rate of the grid as the equivalent firm capacity (EFC) constraint is considered. Then, the constraint is converted into a set of linear chance conditions through the distributionally robust method so that the capacity assessment of the HDR-PV HPS can be converted into a mixed-integer linear optimization problem for a solution. The proposed assessment method is verified by real HDR-PV HPS in the Gonghe Basin of Qinghai Province. The results show that the flexible HDR plant increases the credible capacity of the HPS by 113.38%. The profit of the flexible HDR plant was increased by 3.02% at the same time. The parameter analysis shows that the HDR-PV HPS obtains the most profit when the allowable fluctuation rate is 7%, but 10% can fully utilize the geothermal. The assessment method can effectively assess the credible capacity of the system under the premise of ensuring the overall economy of the HPS, thereby guiding power grid dispatching.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jun Sugiyama ◽  
Kazuki Ohishi ◽  
Ola Kenji Forslund ◽  
Martin Månsson ◽  
Stephen P. Cottrell ◽  
...  

Abstract The diffusive behavior in a spinel-type Li+ ion battery material, Li[Ni1/2Mn3/2]O4, has been studied with positive and negative muon spin rotation and relaxation (μ ±SR) measurements in the temperature range between 200 and 400 K using a powder sample. The implanted μ + locates at an interstitial site near O2− ion so as to form a O–H like bond, while the implanted μ − is mainly captured by an oxygen nucleus, resulting in the formation of muonic oxygen. This means that local magnetic environments in Li[Ni1/2Mn3/2]O4 were investigated from the two different sites in the lattice, i.e., one is an interstitial site for μ +SR and the other is an oxygen site for μ −SR. Since both μ +SR and μ −SR detected an increase in the fluctuation rate of a nuclear magnetic field for temperatures above 200 K, the origin of this increase is clearly confirmed as Li diffusion. Assuming a random walk process with the hopping of thermally activated Li+ between a regular Li site and the nearest neighboring vacant octahedral sites, a self-diffusion coefficient of Li+ was found to range above 10−11 cm2/s at temperatures above 250 K with an activation energy of about 0.06 eV.


2021 ◽  
Vol 6 (1) ◽  
Author(s):  
V. Ukleev ◽  
K. Karube ◽  
P. M. Derlet ◽  
C. N. Wang ◽  
H. Luetkens ◽  
...  

AbstractIn chiral cubic helimagnets, phases of magnetic skyrmions—topologically protected spin whirls—are stabilized by thermal fluctuations over a narrow region directly below the magnetic ordering temperature Tc. Due to often being touted for use in applications, there is a high demand to identify new ways to stabilize equilibrium skyrmion phases far below Tc where they may display an enhanced robustness against external perturbation due to a larger magnetic order parameter. Here, from quantum beam experiments on the chiral magnet Co7Zn7Mn6, we unveil a direct correlation between the stability of its second skyrmion phase-stable far from Tc, and a concomitant enhancement of an underlying magnetic fluctuation rate that is driven by geometric magnetic frustration. The influences of other leading skyrmion stability mechanisms, such as those derived from thermal fluctuations and low T cubic anisotropies, are shown to be weak in this system. We therefore advance the existence of a fundamental mechanism for stabilizing topological skyrmions in Co7Zn7Mn6 chiral magnet that draws upon magnetic frustration as the key ingredient.


Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1287
Author(s):  
Igor Freitas Cruz ◽  
Jaime Sampaio

Research in football has been embracing the complex systems paradigm in order to identify different insights about key determinants of performance. The present study explored the multifractal properties of several football-related scenarios, as a candidate method to describe movement dynamics. The sample consisted of five footballers that were engaged in six different training situations (jogging, high intensity interval protocol, running circuit, 5 vs. 5, 8 vs. 8 and a 10 vs. 10 small-sided game). All kinematic measures were collected using a 100 Hz wireless and wearable inertial measurement unit (WIMUPRO©). Data were processed using a discrete wavelet leader transform in order to obtain a spectrum of singularities that could best describe the movement dynamics. The Holder exponent for each of all six conditions revealed mean values h < 0.5 indicating presence of long memory with anti-correlated behavior. A strong trend was found between the width of the multifractal spectrum and the type of task performed, with jogging showing the weakest multifractality ∆h = 0.215 ± 0.020, whereas, 10 vs. 10 small-sided game revealed the strongest ∆h = 0.992 ± 0.104. The Hausdorff dimension indicates that a maximal fluctuation rate occurs with a higher probability than that of the minimal fluctuation rate for all tasks, with the exception of the high intensity interval protocol. Moreover, the spectrum asymmetry values of jogging, running circuit, 5 vs. 5, 8 vs. 8 and 10 vs. 10 small-sided games reveal their multifractal structures are more sensitive to the local fluctuations with small magnitudes. The multifractal analysis has shown a potential to systematically elucidate the dynamics and variability structure over time for the training situations.


Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 436 ◽  
Author(s):  
Ilya G. Shenderovich ◽  
Gleb S. Denisov

The location of a mobile proton in acid-base complexes in aprotic solvents can be predicted using a simplified Adduct under Field (AuF) approach, where solute–solvent effects on the geometry of hydrogen bond are simulated using a fictitious external electric field. The parameters of the field have been estimated using experimental data on acid-base complexes in CDF3/CDClF2. With some limitations, they can be applied to the chemically similar CHCl3 and CH2Cl2. The obtained data indicate that the solute–solvent effects are critically important regardless of the type of complexes. The temperature dependences of the strength and fluctuation rate of the field explain the behavior of experimentally measured parameters.


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